Diabetes is a disease characterized by chronic hyperglycemia which means elevation of plasma glucose levels over prolonged periods. This happens when a hormone called insulin works improperly to reduce plasma glucose levels. Chronic hyperglycemia due to diabetes leads to micro- or macro-vascular complications. We investigate the association between alcohol consumption and the risk of many diseases including diabetes mellitus and its complications using our large database. To clarify the association between moderate levels of alcohol consumption and the risk of many diseases leads to the health promotion and the disease prevention.