Insulin resistance, impaired glucose tolerance and type 2 diabetes in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is often associated with insulin resistance. Consequences of insulin resistance include:

  • exacerbation of ovarian androgen overproduction and suppression of sex hormone–binding globulin (SHBG), leading to increased bioavailability of androgens
  • development of impaired glucose tolerance or type 2 diabetes; risk is increased several-fold compared to individuals without PCOS.

Individuals with PCOS at high risk of type 2 diabetes include those with:

  • a body mass index (BMI) higher than 25 kg/m2 for Caucasians or 23 kg/m2 for Asians
  • an impaired fasting serum glucose concentration
  • impaired glucose tolerance
  • a family history of diabetes
  • a history of gestational diabetes
  • hypertension
  • high-risk ethnicity (eg Africans, Aboriginal and Torres Strait Islander peoples, and South East Asians).

Screen all individuals with PCOS using fasting blood glucose, HbA1c or an oral glucose tolerance test (OGTT), and repeat every 1 to 3 years. Initial screening with an OGTT is preferred in individuals with PCOS who are at high risk of type 2 diabetes, or who are contemplating pregnancy, because it is the most sensitive test.

Note: Screen all individuals with PCOS for abnormalities of glucose metabolism every 1 to 3 years.

Dietary and exercise measures, as outlined for weight management, can improve insulin sensitivity and reduce the risk of developing type 2 diabetes. Although studies in individuals with PCOS are lacking, studies in other populations suggest exercise may reduce insulin resistance in the absence of weight loss.

Metformin is recommended for individuals at high risk of developing type 2 diabetes, even if current tests of glucose metabolism are normal. Metformin has also been shown to counter other sequelae of insulin resistance in PCOS (ovarian androgen overproduction and suppression of SHBG). For information on the role of metformin in PCOS, see here.

If an individual with PCOS is diagnosed with type 2 diabetes, see Metformin for adults with type 2 diabetes.

For further details on screening and management of insulin resistance, see the International evidence-based guideline for the assessment and management of polycystic ovary syndrome  and the PCOS Practice Tools for Health Practitioners .