Changes in glucose tolerance over time in women with polycystic ovary syndrome: A controlled study

We performed this study to access the changes in glucose tolerance over time in a group of women with polycystic ovary syndrome ( PCOS) ( n = 71) and control women ( n = 23) with regular menstrual cycles and baseline normal glucose tolerance. Mean follow-up was between 2 and 3 yr for both groups ( PCOS 2.5 +/- 1.7 yr; controls 2.9 +/- 2.1 yr). Based on World Health Organization glucose tolerance categories, there was no significant difference in the prevalence of glucose intolerance at follow-up in the PCOS group. In the PCOS group, 25 (37%) had impaired glucose tolerance (IGT) and seven (10%) had type 2 diabetes mellitus at baseline, compared with 30 (45%) and 10 (15%), respectively, at follow-up. There were also no differences within groups ( PCOS or control) or between groups ( PCOS vs. control) in the oral glucose tolerance test-derived measure of insulin sensitivity, but in the women with PCOS who converted to either IGT or type 2 diabetes mellitus, there was a significant decrease ( P < 0.0001). At the follow-up visit, the mean glycohemoglobin level was 6.1 +/- 0.9% in women with PCOS vs. 5.3 +/- 0.7% in the control women ( P < 0.001). Women with PCOS and baseline IGT had a low conversion risk of 6% to type 2 diabetes over approximately 3 yr, or 2% per year. The effect of PCOS, given normal glucose tolerance (NGT) at baseline, is more pronounced with 16% conversion to IGT per year. Our study supports that women with PCOS ( especially with NGT) should be periodically rescreened for diabetes due to worsening glucose intolerance over time, but this interval may be over several years and not annually.