Potential side effects of common diabetes drugs* Sulfonylureas: low blood sugar, upset stomach, skin rash or itching, weight gain Biguanides/Metformin: sickness with alcohol, kidney complications, upset stomach, tiredness or dizziness, metal taste Alpha-glucosidase inhibitors: gas, bloating and diarrhoea Thiazolidinediones: weight gain, risk of liver disease, anaemia risk, swelling of legs or ankles, Meglitinides: weight gain, low blood sugar