Counterpoint: The Oral Glucose Tolerance Test Is Superfluous

The oral glucose tolerance test (OGTT) has been used in clinical medicine for nearly 90 years (1). As heretical as this may sound, it is time for it to be retired. It no longer provides unique and important clinical information that cannot be obtained by other means. The main reason for performing it is to diagnose impaired glucose tolerance (IGT) or diabetes by virtue of the 2-h value (2,3). Both of these are risk factors for cardiovascular disease (CVD) (4,5), and IGT predicts the development of diabetes (6). However, abnormal carbohydrate metabolism is only one of a number of risk factors for CVD, the combination of which is termed the insulin resistance syndrome. Clinically, the insulin resistance syndrome is diagnosed if three of the following five risk factors for CVD are present: central obesity (waist circumference >88 cm in women and >102 cm in men), elevated triglyceride concentrations (>1.7 mmol/l or 150 mg/dl), decreased HDL cholesterol levels (<1.0 mmol/l or 40 mg/dl in men, <1.3 mmol/l or 50 mg/dl in women), hypertension, and hyperglycemia (impaired fasting glucose, IGT, or diabetes) (7). Two articles in this issue of Diabetes Care demonstrate that the 2-h value on the OGTT adds nothing (8) or very little (9) for identifying CVD risk if the other risk factors are taken into account. Stern et al. (8) followed 2,662 Mexican Americans and 1,595 non-Hispanic whites who were between 25 and 64 years of age and did not have diabetes or CVD at baseline for 7–8 years. Addition of 2-h glucose values from the OGTT to models incorporating readily available CVD risk factors did not improve their power to predict CVD. More specifically, further unpublished analysis of these data revealed that if 1,000 people were screened for CVD risk factors and those …