Glycomet (metformin) is an oral anti hypoglycemic agent(reduces blood sugar).It does not cause heavy menstrual bleeding. If you have a history of Diabetics along with irregular periods, I recommend getting checked for Poly cystic ovarian syndrome(PCOS). Before coming to a conclusion I would also like to more history about you age,menstrual history, obstetric history,weight and so on.The best recommendation is to follow up with your Physician to discuss more regarding this possibility . You might need more investigations including checking blood hormone levels, Ultrasound pelvis(to look for PCOS), Thyroid hormone levels(Abnormal thyroid function can cause menstrual irregularities) , hemoglobin levels and complete blood count(to rule out anemia since you have been having heavy menstrual bleeding) If PCOS is diagnosed then you will have to continue metformin to control blood sugar, control weight and may require additional treatment according to your response . Metformin have few side effects. Upset stomach can occur in the beginning but will decrease as your body gets used to the medication. If nausea, vomiting, confusion,abdominal pain occurs when taking Metformin ,you need to go the nearest hospital immediately, as this can be symptoms of rare but life threatening side effect of the drug,Lactic Acidosis. Metformin should not be taken during pregnancy and in patients with kidney diseases. Renal function tests (serum creatinine and blood urea nitrogen) should be checked every 3 months in the beginning and every 6 months later. I recommend you continuing Metformin, monitor blood sugar levels and follow up with your physician as soon as possible to talk about the possibilities we discussed here. Hope I was able to help you Please feel free to address any questions or concerns Regards Lekshmi