Ninety-seven women with polycystic ovary syndrome (PCOS) were tested for insulin resistance and glucose tolerance by means of the continuous infusion of glucose with model assessment (CIGMA) test. The mean concentrations of glucose and insulin at 50, 55 and 60 min of glucose infusion were interpreted using a mathematical model of glucose and insulin homeostasis, and an insulin resistance index (IR1) was obtained. Using insulin and glucose values at 60 min only, a new insulin resistance index (IR2) was obtained using the same mathematical method. In addition, fasting insulin, fasting C-peptide, fasting glucose, fasting insulin:glucose ratio and fasting C-peptide:glucose ratio were also used to assess insulin resistance. There were significant correlations between IR1 and IR2, fasting glucose, fasting insulin, fasting insulin:glucose ratio, fasting C-peptide:glucose ratio. IR2 had the highest correlation with IR1 (r = 0.97, p < 0.001) and provided the best combination of sensitivity (82.9%), specificity (93.9%), positive predictive value (91.9%) and negative predictive value (86.8%). In conclusion, the simplified CIGMA test, using insulin and glucose concentration at 60 min of glucose infusion only, is a highly sensitive and specific measure of insulin sensitivity in women with PCOS.