Mitochondria, tiny energy factories in muscle cells, were long thought to function poorly in people with type 1 diabetes. But new research from physiologist Richie Goulding of VU Amsterdam challenges this idea, showing that lifestyle and fitness, not diabetes itself, have the biggest impact on muscle health.
People with type 1 diabetes cannot produce insulin, which is crucial for getting sugar from the bloodstream into the body’s cells. This causes problems with keeping blood sugar levels stable, which over time can cause damage to many different organs in the body. “After a meal, about 80% of the sugars we ingest end up inside our muscle cells”, physiologist Richie Goulding explains. “Most of this sugar will end up being broken down by our mitochondria, the energy-producing structures in our cells.”
Previous research suggested that people with type 1 diabetes have poor mitochondrial function, making blood sugar control even more difficult. Goulding: “Impaired muscle health can significantly impact the ability of type 1 diabetes patients to manage their blood glucose levels and, ultimately, their disease.”
But Goulding discovered that many of these previous studies compared people with type 1 diabetes to healthy individuals, without taking account of how fit those groups were. A crucial oversight, according to the physiologist. “The main determinant of mitochondrial health is physical activity,” he explains. “If someone becomes more active, their mitochondria improve, and they get fitter. Without accounting for fitness, researchers may mistake differences in mitochondrial function as a disease effect rather than a result of varying activity levels.”
Complicating this further, people with type 1 diabetes are, on average, less fit than the general population. “If you randomly sample people with diabetes, you’re more likely to select a group with lower fitness, increasing the chances of finding mitochondrial differences,” Goulding adds.
Lifestyle choices
To address this, Goulding compared individuals with type 1 diabetes to healthy counterparts with similar age, sex, BMI, and fitness levels, measured by maximal oxygen uptake. He found no significant differences in mitochondrial function, structure, or overall muscle health between the two groups.
A closer look showed that high BMI, poor blood sugar control, and low fitness levels were linked to poor mitochondrial health in people with type I diabetes. However, factors like age, sex, and disease duration had little impact. This suggests that modifiable lifestyle choices, rather than the disease itself, determine mitochondrial health for people with type 1 diabetes.
Implications
Rather than mitochondrial dysfunction being an unavoidable consequence of the disease, it is influenced by exercise, blood sugar management, and maintaining a healthy weight. Clinicians and exercise physiologists can use this knowledge to encourage personalized exercise programs and lifestyle modifications for individuals with type 1 diabetes to support better muscle health and metabolism.
In short, this study highlights the importance of staying active, keeping blood sugar levels stable, and managing body weight to maintain healthy mitochondria. Goulding: “We hope that these findings can be seen as a positive message for patients, because they suggest that it isn't the disease itself that determines negative mitochondrial health outcomes, but rather, how the disease is managed.”
The research is published in Diabetologia (the journal of the European Association for the Study of Diabetes [EASD])