Despite the common stereotype of type 2 diabetes being the result of excess body weight or eating too much sugar, it has long been known that a person’s genetic makeup plays a major role in their risk for the disease. That doesn’t mean, though, that your genetic risk predetermines whether you develop diabetes — for most people, genes interact with environmental factors like what you eat, how much physical activity you get, and what level of body weight you maintain to determine diabetes-related outcomes. In fact, we noted earlier this year that genetics and socioeconomic status (income, education level, and employment status) were both found to be independent factors in the risk for type 2 diabetes.
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For the latest analysis, researchers looked at the lifetime risk of developing type 2 diabetes in 15,671 people of European ancestry ages 45 and older. At the beginning of the study, none of the participants had diabetes, and the researchers looked at their genetic makeup — across a variety of genes known to contribute to diabetes risk — to calculate an estimated lifetime risk of developing type 2 diabetes based on genetics alone. They then looked at who actually developed type 2 diabetes over time — based on standard diagnostic guidelines, or the recorded use of glucose-lowering medications — and looked at the effect a normal body weight had on the risk of developing diabetes in people with a low, medium, or high genetic risk for the condition. A normal weight was defined as a body-mass index (BMI, a measure of body weight that takes height into account) of 25 of lower — in other words, not overweight or obese.
Maintaining a normal body weight found to help prevent type 2 in those at genetic risk
The researchers found that at age 45, the overall lifetime risk for 2 diabetes in one study group (known as ARIC) was 33.2% for those with a low genetic risk, 41.3% for those with a medium genetic risk, and 47.2% for those with a high genetic risk. Among those who maintained a normal body weight, the risk for diabetes was lower in every genetic risk category — but to different degrees. Those who maintained a normal weight were 24.0% less likely to develop diabetes if they had a low genetic risk, 36.3% less likely to develop diabetes if they had a medium genetic risk, and 25.0% less likely to develop diabetes if they had a high genetic risk. In other words, a healthy body weight had the biggest effect on avoiding type 2 diabetes in people with a medium genetic risk for the condition.
In another study group (known as the Rotterdam study), the overall lifetime risk for 2 diabetes was 22.8% for those with a low genetic risk, 30.6% for those with a medium genetic risk, and 35.5% for those with a high genetic risk. Those who maintained a normal weight were 8.6% less likely to develop diabetes if they had a low genetic risk, 31.3% less likely to develop diabetes if they had a medium genetic risk, and 29.4% less likely to develop diabetes if they had a high genetic risk — also showing the largest effect of a healthy body weight in those with a medium genetic risk, but nearly as great an effect in those with a high genetic risk.
The researchers concluded that while “genetic variants for type 2 diabetes have value in estimating the lifetime risk of type 2 diabetes,” it’s also evident that “normal weight mitigates partly the deleterious effect of high genetic risk.” Particularly for people with a higher genetic risk for type 2 diabetes, these results highlight “the importance of obesity prevention in type 2 diabetes prevention.”
Want to learn more about weight management? Read “Tried and True Weight-Loss Techniques,” “Losing Weight Without Feeling Hungry: Eight Tips,” and “Seven Ways to Lose Weight.”