History and exam

Key diagnostic factors

Key risk factors include older age; overweight/obesity; black, Hispanic, or Native American ancestry; family history of type 2 diabetes; history of gestational diabetes; presence of pre-diabetes; physical inactivity; polycystic ovary syndrome; hypertension; dyslipidaemia; or known cardiovascular disease.

One unifying theory postulates the existence of a metabolic syndrome that includes diabetes mellitus, hypertension, dyslipidaemias, and obesity, and predisposes to coronary heart disease, stroke, and peripheral artery disease.[49] However, this theory is not universally accepted as more clinically useful than assessing individual cardiovascular risk factors.[50]

It is very common for type 2 diabetes to be asymptomatic and detected on screening. Symptoms, when present, may indicate more overt hyperglycaemia.

Most commonly vaginal, penile, or in skin folds.

Cellulitis or abscesses.

Cystitis or pyelonephritis.

Other diagnostic factors

Increased fatigability may be an early warning sign of progressive cardiovascular disease; clinicians should have a low threshold for cardiac evaluation.

Due to elevated glucose.

Usually in patients with fasting plasma glucose >16.6 mmol/L (>300 mg/dL), HbA1c >95 mmol/mol (>11%).

Usually in patients with fasting plasma glucose >16.6 mmol/L (>300 mg/dL), HbA1c >95 mmol/mol (>11%).

Usually in patients with fasting plasma glucose >16.6 mmol/L (>300 mg/dL), HbA1c >95 mmol/mol (>11%).

May occur in the extremities as a result of neuropathy in those with prolonged undiagnosed diabetes.

Due to glucose-induced diuresis.

If marked hyperglycaemia is present.

A velvety, light brown-to-black marking, usually on the neck, under the arms, or in the groin. Can occur at any age. Most often associated with obesity. com.bmj.content.model.Caption@722c4d3d[Figure caption and citation for the preceding image starts]: Acanthosis nigricans involving the axillaFrom the collection of Melvin Chiu, MD; used with permission [Citation ends].

Risk factors

Older patients are at increased risk. However, the incidence of type 2 diabetes in children and adolescents is increasing.[12]

Appears to be the precipitating factor leading to clinical expression of diabetes. The mean body mass index (BMI) at the time of diagnosis of diabetes in several studies is around 31 kg/m², and there is a graded increase in risk of diabetes with increasing BMI.[13] Clinical trials have shown that weight loss is associated with delayed or decreased onset of diabetes in high-risk adults.[14]

About 50% of women who have gestational diabetes mellitus will go on to develop overt diabetes mellitus within 10 years of delivery.[15]

Major risk factor for onset of type 2 diabetes. Progression from pre-diabetes to overt type 2 diabetes occurs at the rate of about 2% to 4% per year.[1][2]

Although the specific genetic profile that confers risk has yet to be fully elucidated, epidemiological observations leave little doubt of a substantial genetic component.[6]

Prevalence of diabetes varies by ethnic group. Differential prevalence rates have been observed for European Americans, Hispanic Americans, and African-Americans,[16] with people of African, Hispanic, or American-Indian ancestry at higher risk of diabetes compared with white people.[17] In the UK, type 2 diabetes is more common in people of African, African-Caribbean, and South Asian family origin.[18] South Asian and East Asian people are at increased risk of developing type 2 diabetes, probably due to an interplay of diet, lifestyle, and genetic factors.[19][20][21][22]

While the impact on increased risk of diabetes is mediated in part through obesity/overweight, several interventions studies indicate that increased levels of physical activity delay or decrease onset of diabetes in high-risk adults.[23][24][25][26]

Elevated risk; should be periodically screened for diabetes.[2]

Often associated with type 2 diabetes. Periodic screening is recommended in people with essential hypertension due to increased prevalence of diabetes.[2]

Especially with low high-density lipoprotein (HDL) and/or high triglycerides: periodic diabetes screening is recommended due to the high prevalence of diabetes in patients with dyslipidaemia.[2]

Periodic diabetes screening is recommended due to the high prevalence of diabetes in patients with peripheral vascular and coronary artery disease.[2]

American College of Cardiology/American Heart Association statements identify a number of additional risk factors for atherosclerotic cardiovascular disease, which include: C-reactive protein ≥2 mg/L; coronary artery calcium score ≥100 Agatston units or ≥75% for age, sex, and ethnicity; and ankle-brachial index <0.9.[27]

Stress provokes release of hormones that elevate glucose, and there is some evidence that life stress may predispose to onset of type 2 diabetes.[28]

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