Written by Gayle Jennings, MS, RD, LDN, CDE

Diabetes affects more than 20.8 million Americans. About 6.2 million are undiagnosed and, therefore, unaware that they have diabetes. Type 2 diabetes, which represents about 90 to 95 percent of cases, is more common in people aged 40 and older and in certain ethnic groups. Those who are obese or lead inactive lifestyles are also more at risk.

More often than not, someone who has diabetes probably knows another family member who has diabetes.

So, does this mean that diabetes runs in a family?

Not necessarily. While type 2 diabetes may have a strong genetic basis in about 30% of patients, the biggest factors are environmental, obesity and sedentary lifestyles. In general, the risk of developing diabetes for a sibling of someone with type 2 diabetes is about the same as that in the general population. One reason diabetes may tend to run in families can be explained as “environmental” risk factors. While obesity and a sedentary lifestyle tend to run in families, it does not imply the sharing of a diabetes gene, but it does put the person at a higher risk of developing type 2 diabetes.

Unfortunately, there is an exception to this statement. If a person develops diabetes, despite being lean and active, then the sibling’s risk is about twice as high as the general population. Or, if the patient has a parent with type 2 diabetes, then the child’s risk is almost three times the general population risk.  Even worse, if both parents have type 2 diabetes, the child has a fourfold risk, or nearly a 50% chance, of developing diabetes.

Another explanation for multiple people in one family having diabetes is “clustering.” Clustering is simply the consequence of the fact that type 2 is so much more common than type 1 diabetes in the general population.

Take heart, prevention of type 2 diabetes is possible. Lifestyle changes, including weight loss and a well-balanced eating plan has been shown to reduce risk by 57%.

Copyright © SIU School of Medicine, Springfield, Illinois
Gayle Jennings is a certified diabetes educator and registered dietitian with SIU Center for Family and Community Medicine.