For updates on diagnosis and management of coexisting conditions during the pandemic, see our topic 'Management of coexisting conditions in the context of COVID-19'.

In the short term, insulin is life-saving in the management of type 1 diabetes because it prevents diabetic ketoacidosis, a potentially life-threatening condition. See our topic Diabetic ketoacidosis.

The long-term goal of insulin treatment is the prevention of chronic complications by maintaining blood glucose levels as close to normal as possible. Generally, glycosylated haemoglobin (HbA1c) goals determine the aggressiveness of therapy, which is in turn individualised.

The National Institute for Health and Care Excellence (NICE) in the UK recommends an HbA1c target level of 48 mmol/mol (6.5%) or lower.[35][37]

  • A less stringent target may be appropriate for some patient groups including very young children, older adults, people with a history of severe hypoglycaemia, and those with limited life expectancies, advanced microvascular or macrovascular complications, or comorbid conditions.[46]

  • If the patient is a child or young person, be aware that a stringent target can cause emotional distress and/or conflict with family members or carers and a compromise may need to be agreed.[35]

  • If the patient is an adult, agree an individualised HbA1c aim with them, taking into account factors such as the person's daily activities, aspirations, likelihood of complications, comorbidities, occupation, and history of hypoglycaemia.[37]

Measure HbA1c levels at least:

  • Every 3 months in children and young people aged under 18 years[35]

  • Every 3 to 6 months in adults.[35]

Optimal glucose levels in type 1 diabetes require attention to diet, exercise, and insulin therapy. All three components should be co-ordinated to minimise symptoms and the risk of complications. Self-monitoring of blood glucose (SMBG) is a core component of self care.

Glucose monitoring in children

Advise children (and/or their family members or carers) to routinely perform at least five capillary blood glucose tests every day.[35]

  • More frequent testing will be needed to support safe exercise and during intercurrent illness.

Children and young people aged under 18 years should aim for:[35]

  • On waking: a fasting plasma glucose level of 4-7 mmol/L (72-126 mg/dL)

  • Before meals at other times of day: a plasma glucose level of 4-7 mmol/L (72-126 mg/dL)

  • After meals: a plasma glucose level of 5-9 mmol/L (90-162 mg/dL)

  • When driving: a plasma glucose level of at least 5 mmol/L (90 mg/dL).[49] 

Give ongoing real-time continuous glucose monitoring (CGM) with alarms to children and young people who have any one of:[35]

  • Frequent severe hypoglycaemia

  • Impaired awareness of hypoglycaemia associated with adverse consequences (e.g., seizures or anxiety)

  • Inability to recognise, or communicate about, symptoms of hypoglycaemia (e.g., because of cognitive or neurological disabilities).

Consider ongoing real-time CGM for:[35]

  • Neonates, infants and pre-school children

  • Children and young people who participate in high levels of physical activity (e.g., sport at a national level)

  • Children and young people with comorbidities (e.g., anorexia nervosa) or who are receiving treatments that can make it difficult to control blood glucose (e.g., corticosteroids).

Glucose monitoring in non-pregnant adults

Teach the patient self-monitoring skills at the time of diagnosis and initiation of insulin therapy. Review these skills with them at least once a year. Include information on:[37]

  • How to measure their blood glucose

  • How to interpret the results

  • What action to take.

Support adults with type 1 diabetes to check their blood glucose at least 4 times a day.[37] Increase to up to 10 times a day if any of the following apply:[37]

  • The patient’s agreed HbA1c target is not met

  • The frequency of hypoglycaemia episodes increases

  • There is a legal requirement to do so (e.g., before driving)

  • While the patient is ill

  • Before, during, and after sport

  • While planning pregnancy, during pregnancy, and while breastfeeding

  • If there is any other reason to know blood glucose levels more than 4 times a day (e.g., impaired awareness of hypoglycaemia; high-risk activities).

Bear in mind that additional testing (more than 10 times a day) might be indicated:[37]

  • If the patient has impaired awareness of hypoglycaemia

  • Depending on the patient’s lifestyle (e.g., if they drive for long periods or have a high-risk job).

In practice, most adults with type 1 diabetes are likely to be checking their blood glucose between 4 and 10 times a day.

Advise adults with type 1 diabetes to aim for:[37]

  • On waking: a fasting plasma glucose level of 5-7 mmol/L (90-126 mg/dL)

  • Before meals at other times of day: a plasma glucose level of 4-7 mmol/L (72-126 mg/dL)

  • After meals: a plasma glucose level of 5-9 mmol/L (90-162 mg/dL) at least 90 minutes after eating

  • Bedtime: a personalised plasma glucose level that takes into account the timing of their last meal and its related insulin dose, and is consistent with the recommended fasting level on waking.

If the patient drives, ensure they are aware of the relevant local advice on plasma glucose level. In the UK, the Driver and Vehicle Licensing Agency (DVLA) advises to aim for a level of at least 5 mmol/L (90 mg/dL) before driving.[49]

Some adults with type 1 may require glucose measurement with real-time continuous glucose monitoring (CGM). Real-time CGM, worn by a patient on a regular basis, may help improve glycaemic levels.[50][51][52] The glucose sensors used in CGM are not reliable at lower ranges of glucose, and thus do not eliminate the need for finger sticks. Development of these systems is ongoing.[53] CGM is also less accurate than traditional capillary blood glucose monitoring methods. However, it provides information on glucose trends, provides alarms to alert patients to impending hypo- or hyperglycaemia, and can reduce episodes of hypoglycaemia.[54][55]

The National Institute for Health and Care Excellence (NICE) in the UK recommends considering real-time CGM if any of the following apply despite optimised insulin therapy and conventional self-monitoring of blood glucose, provided CGM can be overseen by a centre with expertise in its use and the patient is able to commit to using it at least 70% of the time and calibrating it as needed:[37]

  • More than one episode a year of severe hypoglycaemia with no obviously preventable precipitating cause

  • Complete loss of awareness of hypoglycaemia

  • Frequent (more than two episodes a week) asymptomatic hypoglycaemia that is causing problems with their daily activities

  • Extreme fear of hypoglycaemia

  • Hyperglycaemia (HbA1c level of 75 mmol/mol [9%] or higher) that persists despite testing at least 10 times a day. Continue real-time CGM only if HbA1c can be sustained at or below 53 mmol/mol (7%) and/or there has been a fall in HbA1c of 27 mmol/mol (2.5%) or more.

NICE is reviewing the guidance with a view to extending the criteria for CGM eligibility to include people with sub-optimal glycaemic control.[37]

Sick-day rules

Give the patient clear and individualised oral and written advice (‘sick-day rules’) about how to adapt management during intercurrent illness.[37][35] This illness plan should include:

  • Monitoring blood glucose

  • Monitoring and interpreting blood ketones (see below)

  • Adjusting their insulin regimen

  • Adapting food and drink intake

  • How to seek further advice.

Ketone monitoring

Ketone monitoring is an additional aspect of management. Insufficient insulin can lead to increased ketone levels which, if untreated, can lead to progressive dehydration and diabetic ketoacidosis (DKA). DKA is a severe life-threatening complication. See our topic Diabetic ketoacidosis.

The risk of DKA is increased if the patient has an illness (e.g., flu or a urinary tract infection) or has missed some insulin doses.

Offer children and young people with type 1 diabetes blood ketone testing strips and a meter. Advise the patient (and/or their family members or carers) to test for ketonaemia if they are ill or have hyperglycaemia.[35]

Consider ketone monitoring (blood or urine) as part of 'sick-day rules' for adults, to facilitate self-management of an episode of hyperglycaemia.[37]

Diet and exercise

Support the patient (and their family members or carers, as appropriate) to develop a good working knowledge of nutrition and how it affects their diabetes.[35][37]

  • There is no standardised dietary advice that is suitable for all individuals with diabetes.[46]

  • Individualised nutrition advice should be based on personal and cultural preferences, health literacy and numeracy, access to healthful food choices, and willingness and ability to make behavioural changes. It should also address barriers to change.

  • Nutritional recommendations should be modified to take into account: excess weight and obesity, those who are underweight, disordered eating, hypertension and renal failure.[37]

  • All patients with diabetes should receive individualised medical nutrition therapy, preferably provided by a registered dietitian who is experienced in providing this type of therapy to diabetes patients.[56]

Carbohydrate counting (with adjustment of insulin dose according to an insulin:carbohydrate ratio) or consistent carbohydrate intake with respect to time and amount may improve glycaemic control. The UK National Institute for Health and Care Excellence (NICE) recommends a low glycaemic index diet to improve blood glucose control in children and young people but does not recommend this approach in adults.[37][35] Rapid-acting insulins may make timing of meals less crucial than in the past, but regular meals are still important.

Encourage the patient to undertake physical activity on a regular basis.

  • Patients with type 1 diabetes can safely exercise and manage their glucose levels.[40][57][58] Be aware that in practice many patients find exercise challenging, particularly as acute exercise increases the risk of dysglycaemia.[58] Therefore the patient will need access to ongoing support, education and input from educators to help them incorporate exercise into daily life.

  • Pre-exercise carbohydrate intake and insulin doses can be effectively modified to avoid hypoglycaemia during exercise and sports.[59]

  • Hypoglycaemia can occur up to 24 hours after exercise and may require reducing insulin dosage on days of planned exercise. A carbohydrate snack (10-20g) should be given at the start of exercise if the patient's blood sugar is <5.0 mmol/L (<90 mg/dL).[58]

The following should be assessed prior to starting an exercise programme: age; physical condition; blood pressure; and presence or absence of autonomic neuropathy or peripheral neuropathy, pre-proliferative or proliferative retinopathy, or macular oedema. Vigorous exercise may be contraindicated with proliferative or severe pre-proliferative diabetic retinopathy. Non-weight-bearing exercise may be advisable in patients with severe peripheral neuropathy.

Be alert to the possibility of bulimia nervosa, anorexia nervosa and disordered eating in patients with type 1 diabetes with:[37]

  • Over-concern with body shape and weight

  • Low BMI

  • Hypoglycaemia

  • Sub-optimal overall blood glucose control.

Consider an early (or if needed, urgent) referral to local eating disorder services for patients with type 1 diabetes who have an eating disorder.[37]

Initiating insulin

Intensive therapy with insulin should be started as soon as possible after diagnosis.[60] Unlike older regimens that used non-physiological insulin dosing, intensive therapy aims to mimic physiological insulin release by combining basal insulin with bolus dosing at mealtimes. Both continuous infusion with an insulin pump and a regimen of multiple daily injections (MDI) can provide intensive therapy.[61] [ Cochrane Clinical Answers logo ] See Regimens below.

Insulin dosing

An initial total daily dose of insulin in adults can be 0.2 to 0.4 units/kg/day. In children, an initial daily dose will be 0.5 to 1.0 units/kg/day, and during puberty the requirements may increase to as much as 1.5 units/kg/day. Often, when first started on insulin, patients with type 1 diabetes will experience a honeymoon period, during which they may require fewer units each day. In general, one half of the total dose is given as basal insulin and one half as bolus dosing.[46] The bolus dosing is divided and given before meals. Basal dose timing varies according to individual patient requirements and the type of insulin used (e.g., insulin detemir is usually given once or twice daily depending on the patient's needs, insulin glargine and insulin degludec are usually given once daily at any time of the day, but preferably at the same time every day). Administration times may vary; check your local guidelines for more information. Patients need to self-monitor their blood glucose levels. In adults, the insulin doses can be adjusted every 2 to 3 days to maintain target blood glucose. Encourage children and young people who are having multiple daily insulin injections to adjust the insulin dose if appropriate after each blood glucose measurement.[35]

To maintain an HbA1c target of 48 mmol/mol (6.5%) or lower, advise adults with type 1 diabetes to aim for:[37]

  • On waking: a fasting plasma glucose level of 5-7 mmol/L (90-126 mg/dL)

  • Before meals at other times of day: a plasma glucose level of 4-7 mmol/L (72-126 mg/dL)

  • After meals: a plasma glucose level of 5-9 mmol/L (90-162 mg/dL) at least 90 minutes after eating

  • Bedtime: a personalised plasma glucose level that takes into account the timing of their last meal and its related insulin dose, and is consistent with the recommended fasting level on waking.

Children and young people aged under 18 years should aim for:[35]

  • On waking: a fasting plasma glucose level of 4-7 mmol/L (72-126 mg/dL)

  • Before meals at other times of day: a plasma glucose level of 4-7 mmol/L (72-126 mg/dL)

  • After meals: a plasma glucose level of 5-9 mmol/L (90-162 mg/dL).

If the patient drives, ensure they are aware of the relevant local advice on plasma glucose level. In the UK, the Driver and Vehicle Licensing Agency (DVLA) advises to aim for a level of at least 5 mmol/L (90 mg/dL) before driving.[49]

The simplest approach to covering mealtime insulin requirements is to suggest a range of doses, such as 4 units for a small meal, 6 units for a medium-sized meal, and 8 units for a larger meal. For greater flexibility of carbohydrate content of meals, pre-meal insulin can be calculated based on the estimated amount of carbohydrate in the meal and the patient's individual insulin-to-carbohydrate ratio. Online structured education programmes can help patients with these strategies - see Structured education below.

Check your local protocol for the recommended insulin-to-carbohydrate ratio. Most adults in the UK are advised to start with a ratio of 1 unit of mealtime insulin for every 10 g of carbohydrate in the meal, although a more conservative approach (e.g., 1 unit per 15g carbohydrate) is more usual practice in some other countries.[62] Patients can use the carbohydrate content per serving listed on food packaging to assess the number of grams in their anticipated meal, but carbohydrate counting is best learned with the help of a dietitian or via a structured diabetes education programme.[37] Using a food diary and 2-hour postprandial blood glucose measurements, the insulin-to-carbohydrate ratio can be adjusted. A correction (or adjustment) dose may be added to the bolus insulin based on the pre-meal blood glucose level. Correction dosing can also be calculated using the patient's total daily dose of insulin (TDD) if food intake is stable. The correction dose can be added to the patient's mealtime insulin requirement (whether based on general meal size or carbohydrate counting) and given as the total bolus dose.


Offer the patient, whether they are an adult or child, a multiple daily injection basal-bolus insulin regimen from diagnosis.[37][35] Do not offer adults newly diagnosed with type 1 diabetes twice-daily mixed, basal only, or bolus only insulin regimens.[37]

Using a combination of long-acting insulin (insulin detemir, degludec, or glargine) for basal dosing, and rapid-acting insulin (insulin lispro, aspart, or glulisine) for bolus dosing, MDI regimens can be designed based on physician and patient preference and modified based on glucose monitoring data. In the UK, NICE recommends for adults:[37]

  • Basal insulin therapy:

    • Offer twice-daily insulin detemir, or one of the following alternatives:

      • An insulin regimen that the patient is established on and meeting their agreed treatment goals

      • Once-daily insulin glargine if the patient cannot tolerate insulin detemir or has a strong preference for once-daily basal injections

      • Once-daily insulin degludec if there is a particular concern about nocturnal hypoglycaemia

      • Once-daily ultra-long-acting insulin, e.g., insulin degludec, if the patient needs help from a carer or healthcare professional to administer injections.

    • Consider other basal insulin regimens if the patient does not meet their treatment goals with the above options, taking into account the patient’s preferences and comorbidities, risk of hypoglycaemia and diabetic ketoacidosis, and any concerns around adherence.

  • Bolus dosing: analogue rapid-acting insulins as the first-line choice.

There is no consensus as to whether insulin analogues are superior to conventional insulins for glycaemic control or reductions in complications.[63][64] [ Cochrane Clinical Answers logo ]

In the past, many patients were managed with twice-daily injections of a mixture of rapid-acting and intermediate-acting insulin. This regimen may be used if patients are unable to safely self-manage with MDI, but it is no longer a first-line recommendation for management because of its lack of flexibility.

An insulin pump (continuous subcutaneous insulin infusion [CSII]) may be considered in some patients for whom MDI regimens are inappropriate or unsuccessful. In the UK, NICE recommends an insulin pump as an option for:[35][65] 

  • Children younger than 12 years for whom MDI therapy is impractical or inappropriate. These patients would be expected to have a trial of MDI therapy at some point between the ages of 12 and 18 years.

  • Adults and children 12 years and older whose attempts to achieve target HbA1c levels with an MDI regimen have resulted in disabling hypoglycaemia with a significant impact on quality of life. The pump should only be continued if it results in a sustained fall in HbA1c levels and/or a reduction in the frequency of hypoglycaemia episodes.

The insulin pump has a subcutaneous insulin infusion port which is changed every 3 days. The pump uses short-acting or rapid-acting insulin, and provides a basal rate of insulin and delivers mealtime bolus dosing. However, the patient (or a parent or carer) must still measure blood glucose frequently (in practice, 4-7 times each day) in order to adjust the pump to deliver the appropriate amount of insulin. Insulin pumps may reduce hypoglycaemia, especially when combined with continuous glucose monitoring (CGM) systems and threshold suspend features, and improve HbA1c, while providing greater flexibility.[54][66][67][68][69] Because of the monitoring and dose adjustment required, use of a pump requires a motivated patient skilled in diabetes self-management and with access to practitioners trained in pump therapy.[70][71] If the patient is a child, they will need strong family support in place.[70]

Insulin pumps with glucose sensors integrated into the same unit are called sensor-augmented insulin pumps. Functionality between sensor and pump has been integrated in one available device: a 'closed loop' system. The basal insulin delivery can be determined automatically based on sensor glucose levels. These integrated devices use a computerised control algorithm to create the hybrid closed loop insulin delivery system, which functions as an artificial pancreas.[40][72][73] In clinical trials, such systems have been shown to reduce the risk of nocturnal hypoglycaemia and to improve glucose control, including in children.[74][75][76] Some models come with smartphone apps that can be used to monitor glucose and insulin dosing. Use of sensors and sensor-augmented pumps is increasing.

Remind the patient to rotate injection sites within the same body region. The Medicines and Healthcare products Regulatory Agency (MHRA) advises this is to prevent or reduce the risk of developing cutaneous amyloidosis (insulin lipodystrophy) at the injection site which may lead to poor diabetes control caused by lack of insulin absorption due to the amyloid mass.[77]

Insulin should not be withdrawn from insulin pen devices or cartridges.[37] NHS England warns that the strength of insulin in pen devices can vary by multiples of 100 units/mL, whereas insulin syringes have graduations only suitable for calculating doses of standard 100 units/mL. If insulin extracted from a pen or cartridge is of a higher strength than intended, and that is not considered in determining the volume required, it can lead to a significant and potentially fatal overdose.[78]

Ensure the risk of medication errors with insulins is minimised by:

  • Prescribing insulins by brand name[37]

    • There are a number of 'sound-a-like' insulins and, in some cases, multiple different strengths and formulations of each type of insulin[79]

  • Following local guidance on minimising the risk of medication error with high strength, fixed combination and biosimilar insulin products.[37] MHRA: High strength, fixed combination and biosimilar insulin products: minimising the risk of medication error external link opens in a new window

Technological advances

There have been significant advances in technology for managing type 1 diabetes. Evolving technology offers the potential to support glycaemic management, reduce complications and the burden and risks of hypoglycaemia, while improving the patient’s quality of life.[80]

In addition to insulin pump therapy and real-time CGM, the advent of intermittently scanned CGM (flash glucose monitoring) empowers the patient to easily access detailed data on their glucose levels, including the direction and rate of change.[80] Flash glucose monitoring, where the patient checks interstitial glucose levels by intermittently scanning a subcutaneous sensor using a reader or a smartphone app, is currently available in many countries for people with type 1 diabetes who meet specific regional criteria. In England, the NHS England criteria, estimated to represent up to 20% of those with type 1 diabetes, span a number of patient groups, including any patient who needs to monitor their blood glucose >8 times per day or who has disabling hypoglycaemia episodes.[81]

Structured education

Accredited online structured education programmes further empower people with diabetes to manage their own condition, by providing remote support to the patient as a complement to their usual appointments.[82]

  • NICE in the UK recommends offering all adult patients with type 1 diabetes access to an evidence-based structured education programme 6 to 12 months after diagnosis.[37]

  • Offer children and young people and their families a continuing education programme from the point of diagnosis that is tailored to take account of age and maturity.[35]

Awareness of hypoglycaemia

Hypoglycaemia is the most common and potentially most serious side effect of insulin therapy. It can lead to decreased quality of life; severe hypoglycaemia is a medical emergency which can cause confusion, seizures, and coma. Severe hypoglycaemia is defined as any low blood glucose level leading to cognitive impairment requiring assistance from another person for recovery. Assess the patient’s awareness of hypoglycaemia at each annual review.[37] In adults, use the Gold score or Clarke score.[37]

Episodes of hypoglycaemia occur with different frequency among patients. Patients should check a 3 a.m. blood glucose if there is concern about risk of nocturnal hypoglycaemia. To manage nocturnal hypoglycaemia (symptomatic or detected on monitoring), review the patient’s knowledge and self-management skills, current insulin regimen, evening eating habits and previous physical activity.[37] Opt for an insulin type and regimen that is less likely to induce low glucose levels at night.[37] A bedtime snack is not always an effective way of decreasing the risk of nocturnal hypoglycaemia.[83] However, a bedtime snack without insulin (or overnight basal insulin reduced by 20%) is recommended if the patient exercises in the afternoon or evening.[57] Bedtime snacks might also be a suitable approach for patients in hospital.

Alcohol may cause acute hypoglycaemia, but both alcohol and exercise can cause delayed hypoglycaemia (by up to 24 hours).

Work with the patient to determine contributing factors, and the ability of the patient to recognise and treat hypoglycaemia appropriately. Advise patients (or parents/carers) that it is important to always have immediate access to a source of fast-acting glucose and blood glucose monitoring equipment so that they can respond quickly to symptoms or signs of hypoglycaemia.[37][35] Train and equip the patient’s family, friends and/or carers (as appropriate) to give intramuscular glucagon for severe hypoglycaemia in an emergency.[37][35]

Immediately treat mild to moderate hypoglycaemia in children and young people with oral fast-acting glucose, e.g., 10-20 g (liquid carbohydrate may be easier to swallow than solid). Fast-acting glucose may need to be given in frequent small amounts, because hypoglycaemia can cause vomiting.[35] Recheck the patient’s blood glucose levels within 15 minutes (fast-acting glucose should raise blood glucose levels within 5-15 minutes), and give more fast-acting glucose if they still have hypoglycaemia.[35] As the patient’s symptoms improve or their blood glucose levels return to normal, give oral complex long-acting carbohydrate to maintain blood glucose levels, unless the child or young person is about to have a snack or meal or having a continuous subcutaneous insulin infusion.[35]

For children and young people with type 1 diabetes who are in hospital, treat severe hypoglycaemia with 10% intravenous glucose if rapid intravenous access is possible. For children and young people with type 1 diabetes who are not in hospital, or if rapid intravenous access is not possible, treat severe hypoglycaemia with intramuscular glucagon or a concentrated oral glucose solution.[35] Do not use oral glucose solution if they have reduced consciousness, because this could be dangerous.[35] Seek senior assistance if the patient’s blood glucose levels do not respond or symptoms continue for more than 10 minutes.[35] As symptoms improve or blood glucose levels return to normal, and once the child or young person is sufficiently awake, give oral complex long-acting carbohydrate to maintain normal blood glucose levels. Check blood glucose repeatedly in children and young people who have persistently reduced consciousness after a severe hypoglycaemic episode, to determine whether further glucose is needed.[35] 

If the patient is an adult and able to ingest orally, hypoglycaemia can be treated with a fast acting form of glucose.[37] If oral intake is not possible owing to a decreased level of consciousness, glucagon is required.[37] This can be administered intramuscularly (by a family member or friend who has been shown how to do this) or intravenously (by a healthcare professional adept at obtaining intravenous access).[37] The patient should be monitored for response at 10 minutes, and then given intravenous glucose if their level of consciousness is not improving significantly. Once it is safe for the patient to have it, they can be given oral carbohydrate. The patient will need continued observation by someone who has been warned of the risk of relapse.[37]

If hypoglycaemia becomes unusually problematic or frequent, review the possible causes including: inappropriate insulin regimens (incorrect dose distributions and insulin types); meal and activity patterns, including alcohol; injection technique and skills, including insulin resuspension if necessary; injection site problems; possible organic causes including gastroparesis; changes in insulin sensitivity (including drugs affecting the renin–angiotensin system and renal failure); psychological problems; previous physical activity; lack of appropriate knowledge and skills for self-management.[37] Consider referring children and young people with type 1 diabetes for assessment of cognitive function if they have frequent hypoglycaemia or recurrent seizures.[35]

Goal not met

If glycaemic levels are not appropriate as measured by the HbA1c or by episodes of hypoglycaemia, re-visit the patient's diet, exercise, and insulin regimen. Children and adolescents may have erratic eating patterns or snack frequently. Consider the possibility of non-adherence to therapy, particularly in adolescent patients.[35] Bear in mind that people with diabetes might be struggling to manage their diabetes effectively owing to psychological and social challenges; these patients will require an integrated multi-disciplinary approach, including psychologists, psychiatrists and support workers.[84] Specifically consider whether an eating disorder, and associated concerns about body size and weight, might be influencing how the patient uses their insulin.[37]

Consultation with a dietitian is an invaluable part of the treatment approach, as patients can learn how to count carbohydrates and adjust their pre-meal insulin to allow for flexibility in meal content and activity. Consistent fasting or overnight hyperglycaemia may require an increase in basal insulin. Pre-prandial and postprandial hyperglycaemia may be due to inadequate insulin coverage for the most recent meal, and may be addressed by considering carbohydrate content of meals, the patient's assessment of their carbohydrate intake, and subsequent pre-meal insulin dosing and timing (around 15 minutes before meals is ideal).

Other conditions contributing to unstable diabetes and that co-exist most commonly with diabetes include coeliac disease, thyroid disease, Addison's disease, and psychosocial distress. Coeliac disease, thyroid disease, and psychosocial distress should be screened for at diagnosis and on a regular basis, while increased clinical suspicion should prompt screening for Addison's disease and pernicious anaemia.

Adjuncts to insulin in adult patients

Consider adding to insulin therapy:

  • Metformin if an adult patient has a body mass index (BMI) of 25 kg/m² or above (23 kg/m² or above for people from South Asian and related minority ethnic groups) and wants to improve their blood glucose control while minimising their effective insulin dose[37] However, the benefits of this approach have been the subject of debate.[85][86]

  • Dapagliflozin if the patient has a BMI of at least 27 kg/m² and insulin alone does not provide adequate glycaemic control despite optimal insulin therapy, as long as:[87]

    • The patient is on insulin doses of 0.5 units/kg of body weight/day or more

    • The patient has completed a structured education programme that is evidence-based, quality assured, delivered by trained educators, and includes information about diabetic ketoacidosis

    • Treatment is started and supervised by a consultant physician specialising in endocrinology and diabetes treatment, and HbA1c levels are assessed after 6 months and regularly after this.

Patients taking dapagliflozin must fulfil these requirements to minimise the increased risk of diabetic ketoacidosis (DKA).[88][89] Stop dapagliflozin if the patient is unwell or dehydrated to reduce their risk of DKA.[90][91]

Planning pregnancy

Infants of women with diabetes are at high risk of major congenital malformations and miscarriage.[92] Pre-conception diabetes care reduces this risk.[93] Pre-conception counselling should, therefore, be incorporated in the routine diabetes clinic visit for all women of childbearing potential.[94] Hyperglycaemia during early pregnancy is associated with an increased risk of congenital anomalies whereas hyperglycaemia in the second and third trimesters is associated with fetal growth acceleration, preterm birth, and neonatal complications.[95] 

Women with type 1 diabetes should use an effective method of contraception until they plan pregnancy.[94]

The National Institute for Health and Care Excellence (NICE) in the UK recommends that HbA1c should be <48 mmol/mol (6.5%) before conception if this can be achieved without problematic hypoglycaemia.[94] Any reduction towards this target is likely to reduce the risk of congenital malformations. NICE recommends up to monthly measurement of HbA1c levels for women with diabetes who are planning a pregnancy.[94]

Women should be evaluated before pregnancy for retinopathy, nephropathy, neuropathy, and possible cardiovascular disease, which may worsen during or complicate pregnancy.[94] In addition to the complications noted above, infants of mothers with hyperglycaemic diabetes are at risk of macrosomia and neonatal distress. Pre-eclampsia is also more common in diabetic pregnancies. Euglycaemia or near-euglycaemia reduces the risk of complications.

Statins, ACE inhibitors, and angiotensin-II receptor blockers should be discontinued before pregnancy (or as soon as pregnancy is confirmed).[94]

Advise women with diabetes who are planning to become pregnant to take folic acid (and continue this until 12 weeks of gestation).[94]

During pregnancy

During pregnancy, women should be cared for by a multi-disciplinary team, including a dietitian, a nurse educator, an endocrinologist, and an obstetrician.

Statins, ACE inhibitors, and angiotensin-II receptor antagonists should be discontinued before pregnancy or as soon as pregnancy is confirmed (alternative anti-hypertensive agents suitable for use during pregnancy should be substituted).[94]

Offer pregnant women with pre-existing diabetes retinal assessment by digital imaging with mydriasis using tropicamide following their first antenatal clinic appointment (unless they have had a retinal assessment in the last 3 months), and again at 28 weeks. If any diabetic retinopathy is present at booking, perform an additional retinal assessment at 16 to 20 weeks.[94]

Advise women with diabetes who are pregnant to take folic acid until 12 weeks of gestation.[94]

  • Women with diabetes have an increased risk of having infants with neural tube defects, compared with the general population.[96]

Intensive insulin treatment with a multiple daily injection (MDI) regimen or insulin pump is important. Commonly used insulins during pregnancy include isophane (NPH), detemir, neutral, lispro, and aspart.[97] The Continuous Glucose Monitoring in Women With Type 1 Diabetes in Pregnancy Trial (CONCEPTT) showed that use of real-time (RT)-CGM during pregnancy in women with type 1 diabetes was associated with improved glycaemic control and neonatal outcomes compared with women who used only self-monitoring of blood glucose (SMBG).[98] In the UK, NICE recommends offering CGM to all pregnant women with type 1 diabetes. Flash glucose monitoring can be offered to any woman who expresses a clear preference for it and/or is unable to use CGM.[94][99] The Association of British Clinical Diabetologists has published guidance on the use of diabetes technology in pregnancy.[95]

NICE recommends isophane insulin as the first-choice for long-acting insulin during pregnancy in diabetes of any aetiology.[94] In practice, in women with type 1 diabetes who are already established on a basal-bolus insulin routine and have achieved good glycaemic control before pregnancy using a long-acting insulin analogue such as detemir or glargine, it may be more appropriate to continue this through pregnancy. There are no large randomised trials supporting the safety of insulin glargine in pregnant patients with diabetes.[100] However, insulin glargine has been safely used in many patients during pregnancy. Limited evidence suggests rapid-acting insulin analogues (aspart or lispro) may be associated with a reduced risk of hypoglycaemia and improved glycaemic control compared with regular human insulin.[94] There are few data comparing outcomes for insulin pump therapy (continuous subcutaneous insulin infusion or CSII) versus multiple daily injections of insulin for pregnant women with diabetes.[101] [ Cochrane Clinical Answers logo ]  One randomised controlled trial reports better glycaemic outcomes with use of multiple daily injection therapy versus insulin pump therapy.[102]

Consider adding metformin to insulin therapy during pregnancy (and in the preconception period), when the likely benefits from improved blood glucose control outweigh the potential for harm.[94] This is most likely to be the case in women who have insulin resistance in addition to insulin deficiency and is a recommended consideration if the woman has a body mass index (BMI) of 25 kg/m² or above (23 kg/m² or above for people from South Asian and related minority ethnic groups) and wants to improve their blood glucose control while minimising their effective insulin dose.[37]

NICE guidelines recommend the following blood glucose targets in pregnant women with pre-existing type 1 diabetes (as long as these are achievable without causing problematic hypoglycaemia):[94]

  • Fasting: <5.3 mmol/L (<95.4 mg/dL), and

  • 1 hour after meals: <7.8 mmol/L (<140.4 mg/dL), or

  • 2 hours after meals: <6.4 mmol/L (<115.2 mg/dL).

Advise pregnant women with diabetes who are on insulin to maintain their capillary plasma glucose level above 4 mmol/L (72 mg/dL).[94]

Measure HbA1c levels in all pregnant women with pre-existing diabetes at the booking appointment to determine the level of risk for the pregnancy. Consider measuring HbA1c levels in the second and third trimesters of pregnancy for women with pre-existing diabetes to assess the level of risk for the pregnancy.[94]

  • The level of risk for the pregnancy for women with pre-existing diabetes increases with an HbA1c level above 48 mmol/mol (6.5%).[94]

Pregnant women should test their fasting, pre-meal, 1-hour post-meal, and bedtime blood glucose levels every day.[94] The pattern should be examined every few weeks early in pregnancy so that nutrition content and timing, exercise patterns, and the insulin doses can be modified to achieve optimal control. Insulin requirements generally increase early in pregnancy, then decrease from about 8 to 16 weeks before rising throughout the rest of the pregnancy.

Advise pregnant women with type 1 diabetes to take aspirin from 12 weeks until the birth of the baby.[94][103]

  • These women are at high-risk of pre-eclampsia.[103]

Ongoing monitoring and support for all patients

The therapy of people with type 1 diabetes also involves management of comorbid conditions (e.g., autoimmune diseases), monitoring to include regular eye examinations, treatment of dyslipidaemia, and blood pressure control. Recommend blood pressure management at 135/85 mmHg for adults with type 1 diabetes. If the patient has albuminuria or 2 or more features of metabolic syndrome, recommend blood pressure management at 130/80 mmHg.[37] Foot care is also an essential part of management.[46][37][35] See Monitoring section.

Psychosocial screening and support can help to ameliorate distress and improve the individual’s and family's capacity for self-care.[104][105][106]

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