Type 2 (non-insulin-dependent) diabetes--an epidemiological overview

Area of Science:

• Epidemiology
• Genetics
• Public Health

Background:

• Type 2 diabetes (non-insulin-dependent) exhibits global distribution with significant variations in prevalence across countries, ethnic groups, and migration patterns.
• Rural-urban and migration studies link a 'Westernized' lifestyle to a marked increase in Type 2 diabetes prevalence.
• Comparisons between populations are complicated by diverse ascertainment rates, survey methodologies, and diagnostic criteria.

Purpose of the Study:

• To analyze the global distribution and prevalence variations of Type 2 diabetes.
• To investigate the influence of lifestyle changes and genetic factors on Type 2 diabetes aetiology.
• To understand the interplay between genetic susceptibility and environmental factors in Type 2 diabetes.

Main Methods:

• Epidemiological studies utilizing diverse methodologies and diagnostic criteria.
• Comparative analysis of prevalence rates across different global populations and ethnic groups.
• Examination of migration and rural-urban transition data to assess lifestyle impacts.

Main Results:

• Lowest Type 2 diabetes prevalence observed in Eskimos and Far East populations.
• Highest prevalence rates found in American Indians, urbanized Pacific Islanders, and migrant Asian Indians.
• Evidence suggests genetic susceptibility ('diabetes genotype') in high-prevalence groups, unmasked by environmental factors.

Conclusions:

• Type 2 diabetes aetiology involves a spectrum of gene-environment interactions, with varying importance of genetic versus environmental roles in different populations.
• Epidemiological studies are crucial for population screening, case-finding, refining diabetes classification, and understanding risk factors.
• Lifestyle changes, particularly Westernization, are significant environmental triggers for Type 2 diabetes in genetically susceptible populations.