ABSTRACT
Diabetes mellitus is a syndrome in which blood glucose levels are inappropriately high for the individual’s physiological state. In most populations both fasting and postprandial plasma glucose levels are continuous variables that are skewed toward the higher range. The differentiation between normal and abnormal is therefore arbitrary and must be defined by additional criteria. Diabetic retinopathy is the most common and easily quantified unique complication of diabetes mellitus. Its prevalence increases linearly with duration of diabetes. For these reasons, the diagnosis of diabetes mellitus has been defined operationally as those blood or plasma glucose levels that predict the future development of diabetic retinopathy (1). Three recent epidemiological studies have provided data on such relationships. Accordingly, diabetes mellitus is defined as described in Table 1 by a fasting plasma glucose 126 mg/dL (7.0 mmol/L) or a 2-h plasma glucose after a 75-g glucose load 200 mg/dL (11.1 mmol/L) (1). However, a dilemma is presented by the observations that macrovascular complications of diabetes mellitus account for its major morbidity and mortality (2,3); we do not know how to define diabetes mellitus as a function of plasma glucose as it relates to the development of macrovascular disease (4,5).
