Screening

Screening for diabetes

The American Diabetes Association (ADA) recommends routine screening of non-pregnant asymptomatic adults of any age with body mass index (BMI) ≥25 kg/m² (≥23 kg/m² for Asian-Americans) in the presence of one or more risk factors for diabetes.[30] In the absence of risk factors, testing is recommended starting at age 35 years.[30]

Risk factors for diabetes include:[30]

  • A history of diabetes in a first-degree relative

  • Physical inactivity

  • African-American or Black, Latino, American-Indian, Asian-American, or Pacific Islander ancestry

  • History of gestational diabetes

  • Hypertension (≥130/80 mmHg or on therapy for hypertension)

  • Dyslipidaemia (high-density lipoprotein cholesterol <0.90 mmol/L [<35 mg/dL] and/or elevated triglycerides >2.82 mmol/L [>250 mg/dL])

  • Cardiovascular disease (CVD)

  • Pre-diabetes (haemoglobin A1c [HbA1c] ≥39 mmol/mol [≥5.7%], impaired glucose tolerance [IGT] or impaired fasting glucose [IFG])

  • Polycystic ovary syndrome

  • Other clinical conditions associated with insulin resistance (e.g., severe obesity, acanthosis nigricans)

Screening should also be considered in people on certain medicines, such as glucocorticoids, statins, thiazide diuretics, some HIV medicines, and second-generation antipsychotic medicines, as these agents are known to increase the risk of diabetes.[30]

If results are normal, the ADA recommends that testing should be repeated at least every 3 years, with consideration of more frequent testing depending on initial results and risk status. People with pre-diabetes (HbA1c ≥5.7% [≥39 mmol/mol], IGT, or IFG) should be tested yearly.[30]

The US Preventive Services Task Force recommends screening for pre-diabetes and type 2 diabetes in adults aged 35 to 70 years who have overweight (BMI ≥25 kg/m² or ≥23 kg/m² for Asian-Americans) or obesity (BMI ≥30 kg/m²).[163] Screening should be considered at an earlier age in patients from a population with a disproportionately high prevalence of diabetes (American-Indian/Alaska Native, Black, Hawaiian/Pacific Islander, Hispanic/Latino).[163] Those with normal test results should be re-screened every 3 years.[163] Those who have pre-diabetes should be referred to effective preventive interventions.[163]

Fasting plasma glucose, plasma glucose 2 hours after 75 g oral glucose, and HbA1c are all appropriate screening tests.[30]

Screening for CVD in people with diabetes

Cardiovascular (CV) risk factors should be assessed at least annually in people with diabetes.[30] This includes an assessment of:[30]

  • Diabetes duration

  • Weight

  • Blood pressure

  • Lipids

  • Smoking status

  • Family history of premature coronary disease

  • Presence of albuminuria (indicator of chronic kidney disease)

One large cohort study found that in those with type 2 diabetes without existing CVD, increased albuminuria levels were associated with higher risk of incident ischaemic stroke, myocardial infarction, and all-cause mortality.[80]

Based on the results of this screening, aggressive medical therapy to reduce CV risk is universally recommended, which may include antihypertensive therapy, lipid-lowering therapy, and, for those with established or high risk of coronary artery disease (CAD), antiplatelet therapy.[30] The American College of Cardiology/American Heart Association atherosclerotic CVD risk calculator should be used to aid with overall CVD risk assessment and the 10-year risk for first CVD event. AHA/ACC: ASCVD risk calculator Opens in new window A European equivalent, known as SCORE2-Diabetes, is recommended by the European Society of Cardiology for use in people aged 40 to 69 years with type 2 diabetes.[7] When HbA1c values are added to CVD risk assessment models, there is little incremental benefit for prediction of CV risk.[164]

While screening for CVD risk factors is important, the benefits of screening asymptomatic people with diabetes for CAD remain unclear, and as such it is not recommended by the ADA.[30] One meta-analysis suggested that systematic detection of silent ischaemia in high-risk asymptomatic people with diabetes is unlikely to provide any major benefit to clinically important outcomes compared with optimised medical management of CV risk factors alone.[165] Another meta-analysis found that routine screening of asymptomatic patients with type 2 diabetes for CAD neither reduced mortality nor reduced a composite of non-fatal myocardial infarction and CV death.[166]

Investigations for CAD should be considered in the presence of any of the following:[30]

  • Typical or atypical cardiac symptoms

  • Abnormal resting ECG

  • Signs and symptoms of associated vascular disease, including carotid bruits, transient ischaemic attack, stroke, claudication, or peripheral arterial disease[30]

Although screening asymptomatic patients for CAD is not recommended, screening for heart failure with B natriuretic peptide (BNP)/N-terminal prohormone B-natriuretic peptide (NT-proBNP) levels can be considered.[30] If abnormal natriuretic peptide levels are detected, echocardiography is recommended. Identification, risk stratification, and early treatment of risk factors in people with diabetes and asymptomatic stages of heart failure have been shown to reduce the risk of progression to symptomatic heart failure.[30]

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