Diabetes is a chronic disease that occurs when the pancreas does not produce enough insulin or when the body cannot effectively use the insulin it produces.Gestational diabetes is hyperglycaemia with blood glucose values above normal but below those diagnostic of diabetes, and symptoms include excessive excretion of urine, thirst, hunger, weight loss, vision changes, and fatigue.Type 2 diabetes is caused by excess body weight and physical inactivity, while Type 1 diabetes is characterized by deficient insulin production and requires daily administration of insulin.