Effect of oral contraceptive use on the incidence of impaired glucose tolerance and diabetes mellitus.

Combined estrogen-progestin high-dose oral contraceptives increase the risk of impaired glucose tolerance which is estimated at approximately 12% of oral contraceptive current users. Glucose tolerance is adversely affected by the chemical structure of the progestins contained in oral contraceptives such as estrane (norethindrone, ethynodiol) and particularly gonane (norgestrel). The women at high risk to develop an impaired glucose tolerance on high-dose, oral contraceptives are those with previous gestational diabetes, with a positive family history of diabetes mellitus in a first-degree relative, or who are obese or older. Low-dose oral contraceptives with a reduced content of estrogen and progestogen such as levonorgestrel or desogestrel as well as the triphasic oral contraceptives containing a low daily dose of levonorgestrel or gestodene, are associated with a significantly lower risk of impaired glucose tolerance, even in women with previous gestational diabetes. Noteworthy however is the ability of low-dose progestogen containing oral contraceptives, such as low dose gonane or estrane oral contraceptives, to induce glucose intolerance by increasing the plasma insulin response to oral glucose. Impaired glucose tolerance is often reversible within 6 months of discontinuing oral contraceptives, except for oral contraceptive users with previous gestational diabetes. Development of diabetes mellitus in high-dose oral contraceptive users is rare.