Diabetes is a chronic, metabolic disease characterized by elevated level of blood glucose (or blood sugar), which leads over time to serious damage to the heart, blood vessels, eyes, kidneys and nerves. The most common is type 2 diabetes (T2D), usually in adults, which occurs when the body becomes resistant to insulin or doesn’t make enough insulin. The number of people living with diabetes rose from 200 million in 1990 to 830 million in 2022. 14% of adults aged 18 years and older were living with this condition, an increase from 7% in 1990. More than half (59%) of adults aged 30 years and over living with diabetes are not taking medication.

As a preventive measure both ACSM (American College of Sports Medicine) and ADA (American Diabetes  Association) recommend comprehensive lifestyle programs that increase physical activity for individuals at risk for T2D which often target weight loss of ∼ 5-10% and an increase in physical activity to either 150 min/week of moderate intensity or 75 min/week of vigorous intensity. Interestingly, there appears to be a dose-response relationship with weight loss and glycemic control as reflected by HbA1c, a measure of average blood glucose levels over an 8-12 week period. Weight loss induced management of T2D in the lifestyle intervention group was also associated with improved cardiovascular health and quality of life. These findings together highlight that T2D can be delayed, prevented and even reversed by exercise.

Most research surrounding exercise on glycemic control has focused on aerobic exercise in people with prediabetes or T2D. Aerobic exercise is rhythmic in nature, with large muscle groups acting to support walking jogging, running, and cycling. Aerobic training increases insulin sensitivity and vascular function among other factors, such as aerobic fitness and reductions in body fat. Resistance training conveys potent benefits to glycemic control and provides additional benefits to muscular strength, bone density, and quantity/quality of muscle. In either case, these studies align with current ACSM and ADA guidelines recommending concurrent training and the inclusion of at least 2 resistance training days in a week. High-intensity interval training (HIIT) has garnered attention over recent years, providing a time-efficient means of improving glycemic control and cardiovascular health in those with T2D. In comparison to other continuous high intensity exercise options, HIIT was reported to be enjoyable for some, despite the stronger feeling of fatigue.

The timing of physical activity for optimal glycemic control has recently become an area of intense research. Timing of activity in a day and with respect to meals are also considered important factor for long-term glycemic control and postprandial glucose spikes. It is important to acknowledge that exercise is also a valuable tool for emotional and mental health. Many patients with T2D develop depression, possibly due to impact of insulin resistance on reward and learning centers in the brain. Regular engagement in some form of moderate intensity aerobic exercise or exercise ‘snacks’ has been shown to improve mood, reduce anxiety and stress, boost self-esteem and improve sleep quality and cognition. Together, these findings support views that exercise can reduce depression in people with T2D, independent of weight loss, via changes in inflammation.

While some of these exercise efforts may not yield changes in body weight over time, exercise trials demonstrate health benefits that extend beyond weight loss such as reductions in visceral fat, liver fat, and systemic inflammation as well as memory and sleep. Therefore, physicians and healthcare providers should encourage exercise and physical activity as a tool to improve/manage glycemia, independent of weight loss, for enhanced health and wellness.