A PROSPECTIVE-STUDY OF ORAL-CONTRACEPTIVES AND NIDDM AMONG US WOMEN

OBJECTIVE - To examine prospectively the association between modem ora l contraceptives with low doses of estrogen and progestin and subseque nt incidence of NIDDM. RESEARCH DESIGN AND METHODS - In a prospective cohort study 98,590 U.S. female nurses aged 25 to 42 and free of diagn osed diabetes, coronary heart disease, stroke, and cancer at baseline in 1989 were followed for 4 years. Endpoint was incidence of confirmed NIDDM. Oral contraceptive use was reported on mailed questionnaires. RESULTS - During 352,067 person-years of follow-up, we confirmed 185 i ncident cases of NIDDM. After adjusting for age, BMI, cigarette smokin g, family history of diabetes, parity, physical activity, alcohol inta ke, ethnicity, history of diagnosis of infertility, elevated cholester ol, and hypertension, women currently using oral contraceptives had a relative risk (RR) of 1.6 (95% CI, 0.9-3.1). For past users, the multi variate RR was 1.2 (95% CI, 0.8-1.8). This association was attenuated after restricting the analysis to symptomatic cases of NIDDM. For curr ent users, RR = 1.3 (95% CI, 0.6-2.8), and for past users, RR = 0.9 (9 5% CI, 0.6-1.4), suggesting that increased surveillance may explain at least part of any excess risk. CONCLUSIONS - In this large prospectiv e study, we found no appreciable increase in the 4-year risk of NIDDM among current users of oral contraceptives. There was no apparent incr ease in risk among past users. The small number of cases reflect the l ow absolute risk of NIDDM in this population of young women.