Purpose of review: The diagnosis of a disease should call forth specific treatment for that disease, or if no specific treatment is available, provide prognostic information for the patient. This review examines the clinical relevance of the current diagnostic criteria for states of abnormal carbohydrate metabolism in asymptomatic individuals.
Recent findings: Ninety percent of asymptomatic individuals whose diabetes is diagnosed by an oral glucose tolerance test and over 99% of those with the risk factors of impaired glucose tolerance and impaired fasting glucose have hemoglobin A1c levels <7.0%, a level not associated with development or progression of diabetic retinopathy or nephropathy. No evidence exists that lowering glycemia is beneficial for cardiovascular disease.
Summary: Clinically, these individuals should be treated with diet and exercise rather than drugs, regardless of their glucose concentrations. A suggested clinically relevant diagnostic approach in asymptomatic individuals is first to measure fasting plasma glucose concentrations. Individuals with values <110 mg/dl need no further work-up, while hemoglobin A1c levels (in a Diabetes Control and Complications Trial, standardized assay) are measured in those with higher fasting glucose concentrations. Hemoglobin A1c levels of 6.1% through 6.9% diagnose prediabetes, while values ≥7.0% diagnose diabetes. In this manner, people at risk for the microvascular complications of diabetes will be given that diagnosis, and others with less carbohydrate abnormalities will be identified for interventions to forestall the development of diabetes and cardiovascular disease.