THE RELATIONSHIP OF INSULIN INSENSITIVITY TO MENSTRUAL PATTERN IN WOMEN WITH HYPERANDROGENISM AND POLYCYSTIC OVARIES

OBJECTIVE Insulin insensitivity is a recognized feature of polycystic ovary syndrome (PCOS) but previous studies have suggested that circula ting insulin concentrations are normal in hyperandrogenaemic women wit h regular cycles. The aim of this study was to examine the relationshi p between insulin sensitivity and menstrual pattern in women with PCO. DESIGN A cross-sectional study of insulin sensitivity in a cohort of PCO subjects with oligomenorrhoea compared to women with PCO and regul ar menstrual cycles and a group of normal control subjects. SUBJECTS S eventy-two women with polycystic ovaries on ultrasonography were studi ed. PCO subjects had clinical and/or biochemical evidence of hyperandr ogenism; 53 had oligo/amenorrhoea (olig) and 19 had regular menses (re g). Results were compared with 31 control subjects. The groups were ma tched for age, weight and ethnic origin. METHODS Glucose and insulin r esponses to 75 g oral glucose were measured. Insulin sensitivity was a ssessed by the decline in plasma glucose following intravenous insulin (0.05 U/kg). RESULTS Glucose area (mean+/-SEM) after oral glucose was increased slightly in both PCO groups compared with controls (olig 37 .6+/-1.4, reg 36.0+/-1.8, control 33.7+/-0.9 mmol/l h, both P < 0.01). Insulin area median (interquartile range) in response to glucose was significantly greater in the oligomenorrhoeic group (346 (239-734) mU/ l h), compared with both PCO with regular cycles (246 (148-355), P < 0 .01) and controls (221 (147-277), P < 0.01). Insulin sensitivity was r educed (P < 0.01) in the oligomenorrhoeic group (147+/-9.2 mumol/l min ) compared to controls (185+/-7.4) but was normal in PCO with regular cycles (182+/-12.5). Insulin sensitivity did not correlate significant ly with plasma testosterone or with SHBG levels, but plasma insulin co ncentrations correlated negatively with SHBG levels (fasting insulin v s SHBG, r= -0.47, P < 0.01; insulin area vs SHBG, r= -0.41, P < 0.01). CONCLUSIONS Insulin insensitivity in polycystic ovary syndrome occurs when there is oligo/amenorrhoea but not when the menstrual cycle is r egular. This is consistent with PCO and insulin insensitivity being se parate abnormalities which when combined are associated with anovulati on.