Prediabetes

Background

• Prediabetes is a high risk state for developing diabetes described as a continuum from normal glucose through worsening elevated glucose and based on the presence of impaired fasting glucose, impaired glucose tolerance, and/or HbA1c 5.7%-6.4%.
• Definitions of impaired fasting glucose and impaired glucose tolerance vary.

Table 1. WHO and ADA Definitions

• Potential complications of prediabetes include (but are not limited to) stroke, coronary artery disease, retinopathy, neuropathy, and nephropathy.
• No symptoms are associated with prediabetes, which is defined by laboratory testing.

Evaluation

• Consider testing to detect prediabetes in asymptomatic persons with risk factors for diabetes.
• Blood testing for diagnosis; all of the following blood tests are considered equally appropriate:
  • HbA1c 5.7%-6.4% (but unclear if HbA1c and same cutoff should be used in children and adolescents)
  • Impaired fasting glucose (IFG), defined as fasting plasma glucose levels 100-125 mg/dL (5.6-6.9 mmol/L) by American Diabetes Association, while World Health Organization and other diabetes organizations use 110 mg/dL (6.1 mmol/L) as lower cutoff
  • Impaired glucose tolerance (IGT), defined as 2-hour plasma glucose 140-199 mg/dL (7.8-11 mmol/L) during 75-g oral glucose tolerance test
• For patients with normal tests, consider repeat testing at least once every 3 years (Weak recommendation).
• If prediabetes is diagnosed, consider testing for other cardiovascular risk factors (Weak recommendation).

Management

• Lifestyle interventions (diet, activity, weight loss, smoking cessation) are first-line treatment.
  • Refer adults with overweight/obesity at high risk for type 2 diabetes to intensive lifestyle behavior change program to achieve and maintain a weight reduction of ≥ 7% of initial body weight through significantly reduced-calorie diet and ≥ 150 minutes/week of moderate intensity physical activity (Strong recommendation).
  • Certified technology-assisted diabetes prevention programs might be effective for type 2 diabetes prevention (Weak recommendation).
  • Emphasize consumption of (Strong recommendation):
    • nutrient-dense foods that are high in fiber (≥ 14 g of fiber per1,000 kcal), minimally processed carbohydrates (such as nonstarchy vegetables, fruits, legumes, and whole grains), and dairy products with minimally added sugar over intake from other carbohydrate sources
    • mediterranean-style diet rich in monounsaturated and polyunsaturated fats to improve glucose metabolism and reduce cardiovascular disease risk
    • foods rich in omega-3 fatty acids (such as fatty fish, nuts, and seeds) to prevent or treat cardiovascular disease
  • Replace consumption of sugar-sweetened beverages with water or low calorie, no calorie beverages and minimize consumption of foods with added sugars (Strong recommendation).
  • Advise all patients not to smoke or use tobacco products, including e-cigarettes (Strong recommendation).
• Glucose-lowering medications
  • Consider metformin therapy for prevention of type 2 diabetes in adults at high risk of type 2 diabetes, particularly in patients with either of the following (Weak recommendation):
    • age 25-59 years with BMI ≥ 35 kg/m², higher fasting plasma glucose (≥110 mg/dL), and higher HbA1C (≥ 6%)
    • history of gestational diabetes mellitus
  • Other pharmacologic therapies that may reduce progression to diabetes in patients with prediabetes, especially in conjunction with lifestyle modification include alpha-glucosidase inhibitors (acarbose, voglibose), orlistat, liraglutide, and glitazones (pioglitazone, rosiglitazone). Glitazones have a BOXED WARNING regarding risk of heart failure, which may preclude use.
• In patients with severe obesity, bariatric surgery may reduce risk of cardiovascular disease in patients with elevated blood glucose levels, reduce risk of type 2 diabetes, and reduce weight.
• Suggested surveillance includes at least annual monitoring for development of type 2 diabetes and screening for (and treating) modifiable risk factors for cardiovascular disease (Weak recommendation).