Heredity plays an important part in diabetes. Genes are passed down from biological parent to child. Genes carry instructions for making proteins that are needed for the body’s cells to function. The key genes may vary in different population groups.
Genes can also increase the risk of diabetes by increasing a person’s tendency to become overweight or obese. One theory, known as the “thrifty gene” hypothesis, suggests certain genes increase the efficiency of metabolism to extract energy from food and store the energy for later use. This survival trait was advantageous for populations whose food supplies were scarce or unpredictable and could help keep people alive during famine. In modern times, however, when high-calorie foods are plentiful, such a trait can promote obesity and type diabetes.