The Roles of Ethnicity, Genetics, and Age in Type 2 Diabetes
Ethnicity and genetics are associated to some degree, and both have a relationship to type 2 diabetes. There are genetic variations that increase the risk for, or make people susceptible to type 2 diabetes. In fact, the risk that a child will develop type 2 diabetes if a parent has type 2 diabetes is a stronger link than for a parent with type 1 having a child with type 1.
But overall, specific genes that are strongly associated with type 2 diabetes have been elusive, even though more than 30 genes have been identified as contributing to an increased risk.
There is nothing elusive about the risk differences associated with ethnicity, however. Whereas again the specific reasons aren’t known, essentially every other ethnic group has a higher risk for type 2 diabetes when compared to non-Hispanic whites. Even more troubling, the occurrence and severity of diabetic complications is greater among those groups, too.
It’s difficult to separate other risk factors such as weight and culture from the data, but researchers who evaluated records on women from the long-term Nurses’ Health Study made adjustments for BMI. Following more than 78,000 nurses who didn’t have diabetes over a 20-year period saw 3,800 cases of type 2 diabetes develop.
In the unadjusted data the risk for type 2 diabetes was 120 percent higher for African- Americans, 76 percent higher for Hispanics, and 43 percent higher for Asians than for whites.
However, adjusting for BMI changed the order making risk 126 percent higher for Asians, 86 percent higher for Hispanics, and 34 percent higher for African-Americans. This suggests that BMI is the greatest risk for Asians and a lower risk for African-Americans. The rates of type 2 diabetes are also higher in Native American populations and Pacific Islanders.
It’s important to point out that the so-called Western diet, high in calories and fat, clearly plays a part in the higher incidence of type 2 diabetes in some ethnic groups. Migrating to the United States is actually a risk factor for type 2 diabetes, and as Western culture and dietary habits spread to other countries, like India, the type 2 diabetes incidence increases there, too.
One piece of good news from the Nurses’ Health Study, however, hinted that a healthy diet cut the risk of developing type 2 diabetes more for other ethnic groups than for whites. That suggests that a healthy diet can do more to control the course of diabetes in these groups where diabetic complications are so common.
Aging increases the risk for type 2 diabetes in all ethnic groups and both genders. Some of the reasons may be exceptionally complicated biochemical changes having to do with insulin output and glucose transport. But there is a clear relationship with a couple of simple and familiar reasons — diet and exercise.
Senior citizens tend to be overweight, and often that weight is carried in the midsection, suggesting visceral fat with its negative effects on insulin sensitivity. Adults in the 45 to 70 age group have the highest rates of obesity on the BMI scale, more than 30 percent, and weight is a defined risk factor for type 2 diabetes.
Not coincidentally, the age groups 65 to 74 and 75+ have the highest rates of type 2 diabetes, more than 20 percent of that population.
Beyond the excess weight, which is likely related to both diet and reduced physical activity, the natural loss of muscle mass that comes with aging could have a role in insulin resistance. Muscles play an important part in getting glucose out of the bloodstream, and fewer muscle cells means fewer places glucose can go.
Maintaining muscle mass with age has many benefits, and preserving insulin sensitivity may be one. Studies measuring insulin sensitivity while building muscle mass with resistance exercise (weight lifting) have shown positive results, and resistance training has become a standard recommendation for aging adults. You don’t need to take up serious pumping iron workouts to get the benefit resistance exercises offer, but feel free if you are so inclined.
Lifestyle changes (weight loss, improved diet, and exercise) have proven to be even more effective than drugs in preventing the progression of prediabetes to diabetes.