Heterogeneity of abnormalities in glucose metabolism in patients with PCOS as result of different diagnostic tools: a practical approach

Introduction: Polycystic ovary Syndrome (PCOS) is the most common endocrine disorder in women of reprocuctive age. Abnormal glucose metabolism is frequent in PCOS and current guidelines recommend an OGTT. However no recommendation exists on the evaluation of insulin resistance (IR), which preceeds diabetes. Gold standard investigating IR is an euglycemic-hyperinsulinemic clamp (IC) but this method is limited in clinical practice.

Methods: 378 patients (age: 29.9 ± 6 y, BMI: 29.1 ± 7.9 kg/m²) with PCOS according to the Rotterdam criteria were included in the study. A 75 g OGTT with analysis of glucose and insulin was done. IR was measured with different established tools: HOMA-IR, Quicki, ISI-Matsuda and AUC (area under the curve).

Results: The OGTT showed normal glucose tolerance in 74%, impaired fasting glucose in 3.8%, impaired glucose tolerance in 21.5% and diabetes mellitus in 3.4%. Including insulin into the analysis increased the number of abnormal findings depending on the method used:

Table 1: Diagnostic indices for insulin resistance

Method	IR criterion	% abnormal	correlation with IC remarks
HOMA-IR	BMI specific	56.4	good, limited at high insulin levels
Quicki	≤0.333	42.7	relatively low, limited at low insulin levels
ISI-Matsuda	≤4.75	57.0	relatively low
AUC	> 7000 uUxmin/ml	46.7	relatively good, trapezoid rule easy to use
HOMA-IR+AUC	BMI specific and/or > 7000uUxmin/ml	64.5

Conclusion: Abnormalities in glucose metabolism are frequent in patients with PCOS. Including the analysis of insulin gives signficant information to the standard OGTT. Evaluating IR requires both fasting and nonfasting conditions, since either of both will miss a considerable number of patients with IR. Using different tools will result in considerable heterogeneity, which may contribute to the variability in studies on glucose abnormalities in PCOS. From a practical standpoint we suggest the combined use of HOMA-IR and AUC, which are both relatively easy to use and well documented. Our data support the necessity of standardization in diagnostic procedures of PCOS.