Polycystic ovary syndrome (PCOS) is a common reproductive endocrine disorder that affects approximately 10% of reproductive age women. It causes menstrual irregularity due to disruption of normal ovulatory mechanisms. PCOS is also associated with increased male hormones in the circulation which cause increased coarse facial/body hair and acne. Many women with PCOS are obese, however lean women can also have PCOS. One of the fundamental metabolic abnormalities in PCOS is insulin resistance. This is especially more common and profound in women who are obese. Resistance to insulin and glucose intolerance can eventually develop into Type 2 diabetes. A few years ago, it was common practice to start women on a medication called Metformin (glucophage) as soon as they are diagnosed with PCOS. Metformin is a medication which improves the sensitivity to insulin. Through subsequent studies we now know that Metformin therapy is only indicated if a woman actually has glucose intolerance, otherwise it is not of any significant benefit. In order to diagnose glucose intolerance it is important to perform a 2 hour glucose tolerance test, a simple fasting glucose is not sufficient. If the diagnosis is made, then the therapeutic dose of Metformin is 1500 mg, if glucose intolerance is not present then it is not to the patient’s benefit to subject them to the side effects of Metformin without any clear benefit. For those patients with PCOS who are reading this, it may be of benefit to discuss with your doctor, whether or not you have been tested for glucose intolerance and if Metformin is of benefit to you.