Some people have an increased risk of developing type 2 diabetes. These include people with cardiovascular disease, hypertension, obesity, stroke, non-alcoholic fatty liver disease, polycystic ovary syndrome (PCOS), a history of gestational diabetes, mental health conditions and people with learning disabilities. Those attending emergency departments, emergency medical admissions units, vascular and renal surgery units and ophthalmology departments may also be at high risk.³⁵

Prediabetes is defined clinically as haemoglobin A1c (HbA1c) level of 42–47 mmol/mol (6.0–6.4%) or a fasting plasma glucose (FPG) level of 6.1–6.9 mmol/l.³⁶ Prediabetes is more than just dysglycaemia; it is associated with an increased risk of all-cause death and CVD in both the general population and in those with established atherosclerotic CVD.³⁷ Risk of death in those with prediabetes, even when glucose levels are normalised, remains higher for those with obesity and lower for those who are physically active.³⁸ 

The recommendations in this section are adapted from sections 1.1–1.3 of the National Institute for Health and Care Excellence (NICE) public health guideline (PH) 38: Type 2 diabetes: prevention in people at high risk.³⁵ These recommendations follow a two-stage strategy to identify people at high risk of type 2 diabetes (or those with undiagnosed type 2 diabetes): risk assessment and subsequent blood testing for those with a high risk score. Whole population-level screening for type 2 diabetes is not recommended. In 2019 the UK National Screening Committee concluded that there is no evidence that population-level screening is more beneficial than not screening. For this reason, we recommend that approaches to risk assessment are targeted.

Encouraging more people to take a risk assessment and testing may add pressure on services, so support from a variety of access points in primary care and the potential for new approaches, such as home testing kits is needed (see the section on Implementing the guideline)

Advice for testing for diabetes in women with PCOS is available from NICE.³⁹

Further information on risk assessment and follow up for cardiometabolic disease in people with psychosis or schizophrenia is available in the Positive Cardiometabolic Health Resource.⁴⁰

Figure 2: risk identification and testing for prediabetes