• M Maliqueo, I Atwater, R Lahsen, F Pérez-Bravo, B Angel, and T Sir-Petermann.
• Department of Medicine, San Juan de Dios Hospital, School of Medicine, University of Chile, Santiago, Chile.
• Hum. Reprod. 2003 Dec 1; 18 (12): 2683-8.

BackgroundThe aim of this study was to establish the effect of polycystic ovary syndrome (PCOS) adjusted for adiposity on proinsulin concentrations.MethodsNinety-one women with PCOS and 72 normal cycling (NC) women were recruited. A 2 h, 75 g oral glucose tolerance test was performed. Glucose and insulin were measured in each sample. Proinsulin and C-peptide were determined at 0 and 30 min and the fasting proinsulin/insulin ratio (PI/I) was calculated. Insulin sensitivity was estimated by insulin sensitivity index (ISI) composite, and beta-cell function was estimated by insulinogenic index.ResultsInsulin, proinsulin and C-peptide concentrations were higher in women with PCOS than in NC women (P < 0.05). PI/I and insulinogenic index were similar in both groups. Proinsulin concentrations increased with body mass index (P < 0.05) only in women with PCOS; therefore, proinsulin concentrations were higher in obese PCOS patients compared with obese control women (P < 0.05). Moreover, a positive association between proinsulin concentrations and waist diameter adjusted for C-peptide (P < 0.05) and a negative association between proinsulin concentrations and ISI composite values were observed in PCOS patients (P < 0.05).ConclusionsData suggest that in PCOS patients an elevated proinsulin concentration could reflect insulin resistance more than beta-cell dysfunction. However, the elevated concentration of proinsulin in these patients could also result from impaired beta-cell function resulting from intra-abdominal obesity independently of insulin resistance.

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