Two major reports have recently revised the classification of and diagnostic criteria for diabetes. Classification was previously based on the need for insulin (insulin-dependent or non-insulin-dependent), but this has become increasingly confusing. Now, the type of diabetes is determined by the etiological process rather than the treatment modality. Type 1 diabetes is thus characterized by islet cell destruction and type 2 diabetes by a combination of defects in insulin secretion and action. An individual with either type of diabetes may be on any treatment modality: This classification should prove to be more logical and, for example, allow latent autoimmune diabetes in adults, which typically does not require insulin at presentation, to be classified as type 1 diabetes. The fasting plasma glucose diagnostic threshold for diabetes has been lowered to 7.0 mmol/l (126 mg/dl), and impaired fasting glucose (fasting plasma glucose 6.1-6.9 mmol/l [110-125 mg/dl]) has been introduced as a new category of intermediate glucose metabolism. These changes recognize that the old fasting threshold did not match the 2-h (postload) threshold well and that both micro-and macrovascular disease develop at lower fasting glucose levels than previously recognized. Although the prevalences of diabetes according to the new fasting and 2-h criteria are now similar in most populations, the actual individuals identified as having diabetes are often different. Over 30% of all those with diabetes have a nondiabetic fasting glucose but still have increased cardiovascular mortality: Thus, it is important to retain the oral glucose tolerance test for the diagnosis of diabetes.