Treatment algorithm
Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer
Primary options
insulin detemir
or
insulin glargine
or
insulin degludec
-- AND --
insulin lispro
or
insulin aspart
or
insulin glulisine
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, multiple daily injections (MDI) regimens can be designed based on physician and patient preference and modified based on glucose monitoring data.
In the UK, the National Institute for Health and Care Excellence (NICE) recommends twice-daily insulin detemir as basal insulin therapy for adults.[37] NICE advises considering one of the following alternatives to twice-daily insulin detemir: 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.[37] If the patient does not meet their treatment goals with these options, NICE recommends considering other basal insulin regimens, taking into account the patient’s preferences and comorbidities, risk of hypoglycaemia and diabetic ketoacidosis, and any concerns around adherence.[37]
NICE recommends analogue rapid-acting insulins as the first-line choice for bolus dosing.[37]
There is no consensus as to whether insulin analogues are superior to conventional insulins for glycaemic control or reductions in complications.[63][64]
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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: 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; at 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.[37]
Children and young people aged under 18 years should aim for: 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).[35]
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.
In adults, a conservative starting approach is to use 1 unit of mealtime insulin for every 15 g of carbohydrate in the meal (bear in mind, however, that the insulin-to-carbohydrate ratio might vary according to local protocols). 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.
Regimens should be individualised to obtain the best possible glycaemic control.
A correction dose may be incorporated into the insulin doses based on pre-meal glucose levels.
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 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.[65]
NICE also recommends a pump as a treatment option for those aged 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; these patients should only continue using a pump if it results in a sustained fall in HbA1c levels and/or a reduction in the frequency of hypoglycaemia episodes.[65]
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]
In addition, follow 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
Treatment recommended for SOME patients in selected patient group
A correction (or adjustment) dose may be added to the bolus insulin based on the pre-meal blood glucose level. In practice, in adults a conservative approach to calculating a correction dose is to assume 1 unit of insulin will lower the patient’s blood glucose by 4 mmol/L (72 mg/dL). 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.
Treatment recommended for SOME patients in selected patient group
Primary options
metformin: adults: 500 mg orally (immediate-release) once daily for at least one week, followed by 500 mg twice daily for at least one week, then 500 mg three times daily thereafter, maximum 2000 mg/day
MoreConsider adding metformin to insulin therapy if the patient is an adult with 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]
This use is off-label in the UK.
Treatment recommended for SOME patients in selected patient group
Primary options
dapagliflozin: adults: 5 mg orally once daily
In adults, consider adding dapagliflozin to insulin therapy 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]
1. The patient is on insulin doses of 0.5 units/kg of body weight/day or more
2. The patient has completed a structured education programme that is evidence-based, quality assured, delivered by trained educators, and includes information about diabetic ketoacidosis
3. 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]
Fixed-dose insulin is used when adult patients are already doing well on a fixed-dose regimen, or cannot manage a multiple daily injection regimen, or have trouble mixing insulin. Various fixed-dose insulin formulations are available; consult your local drug formulary for options.
Primary options
insulin isophane human (NPH)
or
insulin detemir
-- AND --
insulin neutral
or
insulin lispro
or
insulin aspart
Secondary options
insulin glargine
-- AND --
insulin neutral
or
insulin lispro
or
insulin aspart
National Institute for Health and Care Excellence (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): 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).[94]
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.
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 who 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]
Treatment recommended for SOME patients in selected patient group
Primary options
metformin: 500 mg orally (immediate-release) once daily for at least one week, followed by 500 mg twice daily for at least one week, then 500 mg three times daily thereafter, maximum 2000 mg/day
MoreConsider 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]
This use is off-label in the UK.
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