Evidence suggests that physical activity can lower blood glucose levels for type 2 diabetes patients by increasing insulin insensitivity. During and after exercise, cells are more capable of using insulin to take in glucose. A recent study published in the Endocrine Society’s Journal of Clinical Endocrinology & Metabolism has found that one out of every five people suffering from type 2 diabetes does not benefit from exercise due to their genetics.

"Since obesity and lack of physical activity are two key risk factors for type 2 diabetes, physicians frequently recommend exercise and other lifestyle interventions to prevent or manage the disease," Dr. Lauren Marie Sparks, of Florida Hospital and the Sanford-Burnham Medical Research Institute, said in a statement. "Most people benefit from an exercise regimen, but our research indicates that a significant minority of individuals with type 2 diabetes do not experience the same improvements in metabolism due to their genes."

Sparks and her colleagues conducted a systematic review of studies in which people diagnosed with type 2 diabetes were asked to participate in various types of physical activity. Researchers also examined animal and genetic studies.

Between 15 and 20 percent of diabetics who were asked to participate in exercise routines did not experience benefits relating to their blood sugar control, insulin sensitivity, or a measurement of fat-burning capabilities, called muscle mitochondrial density. Animal and genetic studies revealed these findings are not so much based on the effect of exercise, but rather a resistance to exercise that is encoded in the DNA of some diabetics. This genetic resistance could be handed down through generations.

"More research is needed to determine which people with or at risk of developing type 2 diabetes will respond to an exercise program and which will not," Sparks added. "Genetic and epigenetic patterns could hold the key to differentiating between the two groups. With that information in hand, we can target specific interventions and treatments to the individuals who will benefit most and identify novel treatment approaches to help those who do not respond to exercise."

According to the Centers for Disease Control and Prevention, around 40 percent of Americans will develop type 2 diabetes at some point in their lives. Both genetic and lifestyle factors play a role in a person’s risk for prediabetes and type 2 diabetes. For example, people who are over the age of 45, overweight, have a family member diagnosed with diabetes, or are physically active less than three times a week are at an increased risk for diabetes.

Source: Stephens N, Sparks L. Resistance to the Beneficial Effects of Exercise in Type 2 Diabetes: Are Some Individuals Programmed to Fail? Journal of Clinical Endocrinology & Metabolism. 2014.