Impact of ecology on development of NIDDM

Diabetes has become a global epidemic. The increased incidence of NIDDM is seen all over the world but there is geographical variation. Certain population groups show increased susceptibility to develop diabetes. The prevalence is lowest in Caucasian whites and highest in Pima Indians and Naurans. Iceland has a particularly low incidence whereas Bahrain is among the countries with highest prevalence. The highest prevalence of diabetes in 2000 was found in Papua New Guiana (15.5%), Mauritius (15%), Bahrain (14.8%), Mexico (14.2%), Trinidad and Tobago (14.1%). Most of the hypotheses developed to explain this trend concerned mainly on dietary and nutritional factors. Man had to struggle against harsh climatic conditions for survival. It has been observed that people who have been adapted to cold environment for generations demonstrate some resistance to develop diabetes. It is hypothesized that presence of thick subcutaneous fat, reactivation of brown adipose tissue in cold environment and effective mitochondrial enzyme systems for heat generation act as adaptive mechanisms for survival in cold environment and retard the development of visceral obesity. Mitochondrial defects have been found in patients with NIDDM and NAFLD. Changes of nuclear genes which encode mitochondrial enzyme systems involved in thermo genesis could be the cause for development of visceral obesity and NIDDM.