Relative risk of conversion from normoglycaemia to impaired glucose tolerance or non-insulin dependent diabetes mellitus in polycystic ovarian syndrome

BACKGROUND: Cross-sectional studies have shown a high frequency of impaired glucose tolerance (IGT) and non-insulin dependent diabetes mellitus (NIDDM) in women with polycystic ovarian syndrome (PCOS). However, little is known about the change in glucose tolerance that occurs over a period of several years in women with PCOS. METHODS: Sixty-seven women with PCOS received a 75 g glucose tolerance test and measurement of lipids at baseline and at follow-up after an average time of 6.2 years. All women followed prospectively had normal glucose tolerance (n=54) or IGT (n=13) at the start of the study. RESULTS: Change in glycaemic control from baseline was frequent, with 5154 (9%) of normoglycaemic women at baseline developing IGT and a further 4/54 (8%) moving directly from normoglycaemic to NIDDM. For women with IGT at baseline, 7/13 (54%) had NIDDM at follow-up. Body mass index (BMI) at baseline was an independent significant predictor of adverse change in glycaemic control. CONCLUSIONS: Women with PCOS, particularly those with a high BMI, should be reviewed regularly with respect to IGT or NIDDM, as the frequency of impaired glycaemic control is high, and that the rate of conversion from normal glucose tolerance to IGT or NIDDM, or from IGT to NIDDM is substantial.