Diabetes mellitus is a clinical syndrome characterized by hyperglycemia (high blood sugar) due to absolute or (partial) relative deficiency of insulin. Lack of insulin affects the metabolism of carbohydrate, protein, fat, water and electrolytes. Long-standing metabolic disturbance causes permanent and irreversible functional and structural changes in the cells of the body which results in death.

Heredity

The heredity plays a vital roll and the heredity pattern of diabetes are very complex and the genetic tendency shows clearly that it is not directly handed on to all the children of an affected generation, although the tendency towards developing it is passed on. In identical twins when one twin develops diabetes, about 70 percent of the other twins will also develop it. But in non-identical twins this happens with less than ten percent. In children with both diabetic mothers and fathers, only one in four subsequently develops diabetes- those with only one diabetic parent develop the disorder at a slightly greater rate than the normal population.

Obesity and diet

The overweight and obese may unable to deal efficiently with the sugar they eat – an inability that later is shown in its more extreme form as diabetes. It has been said that overeating throws an excessive strain on the pancreas, a strain that in the end causes its failure. It may be, however, that those who become obese, and consistently overeat, are prone to diabetes through inheritance. The evidence of control in diabetes by diet does show, that a high blood sugar can be reduced and sugar in the urine eliminated by diet alone and this suggests that the cause and the effect are closely associated.

Virus

The epidemiological studies and isolated case reports show that viruses like mengo virus 2T directly destroys the pancreatic beta cells and certain individuals fail to produce the anti-bodies against certain diabetes causing viruses.

Immunological factors

Detailed  studies have produced evidence that the insulin secreting cells in the pancreas is destroyed slowly and then the symptoms of the disease appears only after almost all the cells are destroyed and this is because of the auto-immunity development.

Inflammation of pancreas

The whole pancreas sometimes affected by disease and the diabetes begins in certain cases.

Emotional stress

Many diabetics find the disorder first diagnosed after a prolonged period of stress in their lives which are connected with the excessive release of stress hormones for a longer period.

Antagonists

Several hormonal antagonists cause the development of diabetes such as growth hormone, human placental lactogen and glucocorticoids.

Medication

Long term use of certain drugs like thiazide diuretics, corticosteroids and phenytoin causes diabetes.