Type 2 diabetes is considered the most common form of diabetes. In fact, it accounts for 90-95% of the total number of diabetes patients.
Obese type 2 diabetes
About 80 percent of people with type 2 diabetes are overweight. This form of diabetes usually develops in adults (age 40 and older). However, as more and more children are becoming overweight, type 2 diabetes is being increasingly noticed in young people.
Type 2 diabetes is often part of a metabolic syndrome (Syndrome X) that includes obesity, high blood pressure and high levels of blood lipids.
Although the pancreas is usually producing sufficient amounts of insulin when type 2 diabetes is diagnosed, the insulin is unable to act effectively, a condition called insulin resistance. Initially, the beta cells of the pancreas try to compensate by producing more insulin to overcome the insulin resistance. After several years, the pancreas become exhausted and insulin production decreases. As a result, the blood glucose starts rising and the patient starts developing symptoms. The role of genetic factors is more significant in type 2 diabetes than in type 1 diabetes. In case of identical twins, there are 90-100% chances that both may suffer from Type 2 Diabetes in case one of them has the disease.
Non-obese type 2 diabetes
In most of these cases the cause is unknown. This type of diabetes usually presents with an absent or poor insulin secretion in response to glucose. However, it may occur in response to other insulinogenic stimuli such as intravenous administration of sulfonylureas, glucagon or arginine. Certain genetic abnormalities have been documented in some of these patients and they have been grouped under “Other specific types”.
Other specific types of diabetes include:
- Maturity-onset diabetes of the young (MODY) is a rare and an autosomal dominant inherited disease. It is a non-insulin dependent type of diabetes beginning at the age of 25 years or younger. These patient are not obese and increased blood glucose results due to secretion of insulin in response to impaired glucose. MODY has been classified into 5 types, with a single gene defect present in any one of the following chromosomes: 20, 7, 12, 13 and 17.
- Diabetes due to mutant insulins is again a rare form of non-obese type 2 diabetes. It appears only after middle age. As the patient has one normal gene (heterozygous) the diabetes is mild.
- Diabetes due to mutant insulin receptors. This type of diabetes may be attributed to some defects in the insulin receptor genes. Most of the cases present with insulin resistance associated with acanthosis nigricans.
- Diabetes mellitus associated with a mutation of mitochondrial DNA. This type of diabetes is inherited from the mother and has been reported in some Japanese families and a few isolated cases in Caucasians. The patients have mild diabetes that responds well to oral hypoglycemic medications. Two third of patients may have a hearing loss and a few patients (15%) may suffer from Myopathy (disease of the muscles), Encephalopathy, Lactic-Acidosis and Stroke like episodes (MELAS).