Abstract—Diabetes mellitus is a disease in which a person's blood sugar level is high either because the pancreas does not produce enough insulin, or the insulin that is produced is not effectively used up by the cells of the body. As a result of these, blood glucose level rises up which spills into the blood. Insulin is a hormone which is needed by the body to convert sugar and other starch into useful energy. Type 1 diabetes is when the body fails to produce adequate amount of insulin. Type 2 diabetes is when the body cannot properly make use of the insulin that is produced. Gestational diabetes occurs in pregnant women. Other forms of diabetes may be congenital or due to use of steroids and glucocorticoids or caused by cystic fibrosis. Diabetes is the world' s fastest growing chronic disease with about 285 million patients. The causes of diabetes are heredity, feeding habits and life style. Symptoms of diabetes are frequent urination, increased thirsts and hunger. The complications of diabetes are cardiovascular diseases, stroke, reduced vision and blindness, kidney damage, diabetic coma, diabetic foot ulcer, and consequently amputation. It can be diagnosed by fasting plasma glucose test, oral glucose tolerance test and use of glucometer. In ancient times, diabetes was a dead sentence. Diabetes is one of the hardest diseases to live with .Presently, there is no known cure for diabetes except in very specific situations .Management of diabetes concentrates on keeping blood sugar level close to normal, healthy life style, regular exercise and good diet.