When enough insulin is not available or when the insulin isn't able to perform its task well, as in Type II diabetes, the body reacts much like a machine running out of fuel.

Glucose is the fuel of the body, the fuel of each and every cell of the body. Insulin provides the key which allows glucose to enter the cells. When enough insulin is not available or when insulin is not able to function, then, the fuel- glucose can't get into the cells, where it is needed; it then builds up in the blood. The unused glucose circulates through the kidneys. When the amount of glucose is more than what the kidneys can handle, the extra glucose spills out into the urine.

• Type I diabetes
• Type II diabetes
• Gestational diabetes

Type I diabetes usually occurs in younger people, children and adolescents

Type II diabetes is the commonest diabetes. It usually occurs after age 40 - but Indians in India, all over the world are getting it at a much younger age.

Another type of diabetes is called "gestational" diabetes. It occurs only during pregnancy. Although, gestational diabetes goes away after the baby is born, women who have had it, are at higher risk for Type II diabetes, later on.

Some individuals may have blood glucose levels above normal but not high enough to be to be labeled as diabetes. This is called "prediabetes" or "impaired glucose tolerance ". It is especially important for these people to make changes in their eating habits, exercise frequently and to lose weight, if needed, to prevent full blown diabetes. Even at this stage diabetes can be prevented and the prediabetes state can be returned back to normal. Regular blood glucose tests should be done by the doctor. This condition may progress to Type II diabetes especially it lifestyle of the individual does not change.