Type 2 Diabetes Causes: Genetic causes, stress, obesity, diet, drugs, endocrine disorders
What are the causes of Type 2 Diabetes?
Type 2 Diabetes is also called as Non Insulin Dependent Diabetes Mellitus (NIDDM) may be defined as diabetes with resistance to ketoacidosis in absence of exogenously administered insulin. Common onset is seen between 35 to 65 yrs.
Metabolic basis of hyperglycemia in Type 2 Diabetes:
Three major defects which determine the final metabolic profile of type 2 DM include are:
- Inefficient glucose utilization by peripheral tissues mainly contributing to post prandial hyperglycemia.
- Impaired basal and stimulated insulin secretion from beta cells.
- An increase in the endogenous hepatic glucose production and release responsible for fasting hyperglycemia.
Genetic factors causing Diabetes
Genetic factors cause insulin resistance
Mutations in the insulin receptor gene cause syndromes of severe insulin resistance in homozygous states.
Maturity onset diabetes of young (MODY), as the name indicates is NIDDM with age onset of less than 25 years. It has an autosomal mode of inheritance.
MODY-1, related to yet unknown gene located on long arm of chromosome 20.
MODY-2 is due to mutation of glucokinase gene on chromosome 7p.
MODY-3, a more severe and often insulin dependent type related to gene on chromosome 12q.
MODY-2 is the commonest, being present in 25 to 50% of the families so diagnosed and is due to reduced activity of glucokinase.Environmental factors causing Diabetes
- Physical activity: reduced physical activity is associated with insulin resistance.
- Diet: consumption of excessive amount of food, particularly high calorie value, is associated with increased prevalence of NIDDM or type two DM. Westernized diet with an excess of energy dense saturated fat and refined carbohydrate rich foods are adding to burden of NIDDM. Lacs of dietary fiber, inadequate consumption of fresh vegetables and fruits as rich source of anti-oxidants are being suspected as additional dietary risk factors.
- Stress: many states of trauma or physical illness are associated with glucose intolerance probably induced by hormonal changes.
- Drugs: drugs for e.g. phenytoin, thiazides, cortico-steroids, and beta-blockers impair glucose tolerance.
- Endocrine disorders: Diabetes may occur in number of endocrine disorders.
- Hormones: Diabetogenic drugs and hormones may reduce tissue insulin sensitivity or impair beta cell function or both.Obesity:
Obesity is a major risk factor for type 2 DM. Probable mechanisms are-
- Increased serum NEFA concentration may cause insulin resistance and reduced beta cell function.
- Adipocyte secretion of proteins and cytokines may contribute to insulin resistance.
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