Everyone with health concerns tries to be as good as they can. We try to stick to diets or exercise routines, but that’s not always possible. Between busy lives, setbacks and other obstacles, things can get in the way of our goals. It happens to everyone! Frequently, when our diet or exercise goals get away from us, we hope that we can make up ground by doubling down on the other aspect of our plan. But, new research shows that the benefits of a good exercise routine can be undone by a high sugar diet.

People with consistently high blood sugar, or hyperglycemia, tend to be overweight and at a higher risk for heart disease and [blood sugar concerns]. Because of those risks, doctors may tell them to turn to diet and exercise to manage their risk factors and improve their health. If they only exercise, they may not see the benefits they are hoping for.

Researchers performed a study where they had two groups of mice. One group was normal; the other group was not overweight but did have high blood sugar. Both groups ran an average of 300 miles during a month and a half. The mice in the first group grew very fit. The mice with high blood sugar saw fewer benefits from their exercise regime. When the researchers looked at the mice’s muscles, the normal mice had grown new muscle fibers and blood vessels. In contrast, the mice with hyperglycemia hadn’t.

“We grow new blood vessels to allow more oxygen to be delivered to the muscle, which helps to increase our aerobic fitness levels,” explained Dr. Sarah Lessard, who performed the research.

They moved to study a group of 24 human volunteers. People with higher blood sugar and worse blood sugar control had lower endurance and higher amounts of proteins in their muscles that resist improvements from exercise.

It wasn’t all bad news. The mice with hyperglycemia did gain endurance as time went on and appeared to have better blood sugar the longer they exercised. Perhaps, over a long course of exercising, the damage could be reversed. And, they lost fat tissue.

“The good news is, although our mouse models of hyperglycemia failed to improve aerobic fitness with training, they still achieved other important health benefits from the exercise, including decreased fat mass and improved glucose metabolism,” Dr. Lessard said. “So, regular aerobic exercise is still a key recommendation for maintaining health in people with or without hyperglycemia.”

While the results may be disheartening at first glance, people with high blood sugar should not just throw in the towel on exercise and focus exclusively on improving their diet. Diet and exercise work in concert with each other to help us become and stay healthy.

“We often think of diet and exercise as separate ways to improve our health,” Dr. Lessard said. “But our work shows that there is more interaction between these two lifestyle factors than what was previously known, and suggests that we may want to consider them together in order to maximize the health benefits of aerobic exercise.”