Management of people at risk of developing type 2 diabetes

People with impaired fasting glucose, impaired glucose tolerance or glycated haemoglobin (HbA1c) of 42 to 46 mmol/mol (6.0 to 6.4%) are often referred to as having prediabetes, and have an increased risk of developing type 2 diabetes and cardiovascular disease (for diagnostic test thresholds, see Diagnostic thresholds for diabetes). For information about identifying people at risk of developing type 2 diabetes, see Screening for type 2 diabetes in asymptomatic adults or Screening for type 2 diabetes in asymptomatic children and adolescents. Children and adolescents with impaired fasting glucose or impaired glucose tolerance should be managed by a specialist diabetes service.

Note: Children and adolescents with impaired fasting glucose or impaired glucose tolerance should be managed by a specialist diabetes service.

Lifestyle modification is the mainstay of management for people identified as being at risk of developing type 2 diabetes. Dietary modification and exercise to achieve a weight loss of 5 to 7% can delay progression to diabetes. There is strong evidence for structured, intensive lifestyle interventions (compared with general lifestyle modification strategies) in patients with impaired glucose tolerance, whereas evidence is less certain in patients with impaired fasting glucose or prediabetes on an HbA1c alone.

Prediabetes is considered a risk factor for cardiovascular disease; cardiovascular disease risk should be assessed and managed (see Cardiovascular disease risk estimation).

Drug treatment has been used to reduce the risk of progression from prediabetes to type 2 diabetes. However, at the time of writing, no antihyperglycaemic drugs are approved by the Australian Therapeutic Goods Administration (TGA) for use in patients with prediabetes. Use shared decision making with the patient to determine whether to start drug treatment for prediabetes in adults. Drug treatment in children and adolescents at risk of developing type 2 diabetes should only be considered with specialist advice.

Metformin had greatest benefit in reducing progression to type 2 diabetes in adults younger than 60 years with a body mass index (BMI) of 35 kg/m² or more, and benefits persisted for up to 10 years. Metformin should be considered if lifestyle modification is not successful. However, there are no clinical outcome studies to show metformin reduced microvascular or macrovascular complications in the longer term in adults with prediabetes.

Acarbose delays development of type 2 diabetes in adults with impaired glucose tolerance. However, the risk of cardiovascular events is not reduced in adults with coronary heart disease and impaired glucose tolerance.

Other drugs reported to reduce the incidence of type 2 diabetes in adults at risk include liraglutide, thiazolidinediones, and the combination of phentermine and topiramate.