Causes
Type 2 diabetes is caused by a complicated interplay of genes, environment, insulin abnormalities, increased glucose production in the liver, increased fat breakdown, and possibly defective hormonal secretions in the intestine. The recent dramatic increase indicates that lifestyle factors (obesity and sedentary lifestyle) may be particularly important in triggering the genetic elements that cause this type of diabetes.
Insulin Abnormalities
The characteristic features of most patients with type 2 diabetes are:
- Insulin resistance in muscle cells
- Normal or even excessive levels of insulin (to compensate for this resistance), eventually followed by a drop in insulin production
In addition, researchers are trying to determine the factors that might promote insulin resistance:
- Both obesity and insulin resistance at different phases are marked by elevated levels of free fatty acids and the hormones resistin and leptin. It is not known yet if elevated levels are simply a product of obesity or play some causal role in diabetes.
- Insulin resistance is associated with a chronic low inflammatory response, which involves a number of immune factors, such as TGH-beta 1 and C-reactive protein. Such factors can cause damage over time and may be responsible for the association between insulin resistance and heart disease.
Genetic Factors
Type 2 diabetes has a genetic component. As one specific syndrome, maturity-onset diabetes of the young (MODY), seems related to one specific gene. Generally, diabetes type 2 is thought to result from a combination of the presence of specific genes along with predisposing environmental factors. Specific mutations may affect parts of the insulin gene and various other physiologic components involved in the regulation of blood sugar.
Most of these genes play a role in regulating insulin action, including the processes that occur in the pancreas’ insulin-producing beta cells. The FTO gene increases the risk for obesity, which itself is a risk factor for type 2 diabetes. These genes appear to cluster around three genetic regions that include a number of chromosomes. Scientists hope that future research will help uncover how genes influence the progression from pre-diabetes to diabetes, and how lifestyle and medical intervention may help delay or prevent this process.
