Endocrine Abstracts

Background: Polycystic ovary syndrome (PCOS), the commonest endocrinopathy of women in the reproductive age is often accompanied by insulin resistance (IR). The aim of the study was to assess the prevalence of IR in women diagnosed with PCOS, where IR was assessed by methods most commonly used in clinical practice, i.e. homeostatic model assessment (HOMA) and insulin resistance index (IRI), also known as the Belfiore index.

Patients and methods: The study involved 137 women diagnosed with PCOS according to the Rotterdam (2003) criteria, age (mean±S.D.) 25±7 years, BMI 27.61±7.43 kg/m². IR was assessed according to the HOMA method (glucose (mmol/l))×(insulin (μU/ml))/22.5 and IRI methods, where IRI, can be obtained through the formula: 2/((1/(INSp×GLYp))+1), where where INSp, GLYp=insulinemic and glycemic, areas during 75 g OGTT. IR was diagnosed for IRI >1.25.

Results: There was a strongly significant (P<0.0001), but still relatively moderate correlation between IRI and HOMA methods (r=0.5 and r=0.57 for a linear and non-linear model respectively). IR was much more prevalent according to IRI (49.6%) than according to HOMA (22.6 and 15.8% for 3.46 and 3.8 cut-off points, respectively, P<0.01). The majority of patients with high HOMA also had high IRI (e.g. 86% for HOMA >3.8), but the majority of patients with raised IRI, would not be diagnosed as insulin resistant according to HOMA (61.7 and 73.5%, for HOMA_3.46 and HOMA_3.80 respectively). IRI concentrations were higher among patients with concomitantly raised HOMA (1.55±0.18 vs 1.44±0.14, P=0.014 and 1.60±0.18 vs 1.44±0.13, P=0.0008 for HOMA_3.46 and HOMA_3.80 respectively).

Conclusions: IRI, based on glucose and insulin measurements during OGTT demonstrates more cases of insulin resistance than HOMA model in women with PCOS. Therefore, detection of insulin resistance among women with PCOS is highly method-dependent with more severe cases being detected with HOMA than with IRI.