Combined oral contraceptive use has been associated with increased incidence of impaired and diabetic glucose tolerance. Although increased risk of overt symptoms of diabetes has not been associated with oral contraceptive use, increased risk of coronary heart disease has been consistently demonstrated. Diabetes is associated with increased risk of coronary heart disease, especially in women. Elevated plasma glucose and insulin concentrations are also associated with increased risk of coronary heart disease. Studies of the effects of low-dose oral contraceptives on glucose tolerance test plasma glucose and insulin levels are reviewed. Low-dose combined oral contraceptives induced changes in measures of carbohydrate metabolism in directions consistent with increased risk of coronary heart disease. The magnitude of these changes may depend on the dose and type of progestogen. The clinical implications of these changes are unknown, but it would seem advisable to minimize them where possible.