A recent review published in Trends in Endocrinology & Metabolism by researchers from the University of Copenhagen and the Karolinska Institute suggests that the timing of exercise is a significant factor in metabolic management, particularly for patients with type 2 diabetes.
Evidence analyzed indicates that physical activity performed in the late afternoon is associated with lower blood glucose levels, improved insulin sensitivity, and more durable metabolic effects that can last up to 24 hours. Conversely, the same exercise performed early in the morning can lead to higher glucose and a less favorable insulin response. This aspect is especially relevant in clinical practice for managing type 2 diabetes.
Circadian rhythm and metabolic response
A key element highlighted by the review is the role of physical activity as a modulator of circadian rhythm. Physiological functions, including insulin secretion, blood pressure, body temperature, and energy metabolism, follow predictable 24-hour oscillations and are regulated by peripheral molecular clocks coordinated by a central clock. In people with type 2 diabetes, these rhythms are often disrupted, creating circadian misalignment that contributes to worsening glycemic control.
Dawn phenomenon and morning exercise
The reduced effectiveness of morning exercise can be explained by the so-called “dawn phenomenon,” characterized by a physiological rise in cortisol in the early morning hours, increased hepatic glucose production, and greater insulin resistance in diabetic patients. Vigorous exercise during this phase can amplify glucose release into the bloodstream, temporarily worsening glycemic profile.
For patients with type 2 diabetes, afternoon exercise may be preferable to optimize glycemic control, while morning activity remains recommended, especially if performed at low intensity, such as brisk walking. It is essential to tailor the timing of physical activity to the patient’s metabolic profile, comorbidities, and lifestyle.
Limitations and future directions
The studies included in the review have some limitations, including small sample sizes, a predominance of middle-aged male subjects, and short intervention durations. The effects of exercise timing on other clinically relevant outcomes—such as cardiovascular risk, sleep quality, and longevity—still need clarification. Despite differences related to the time of day, the clinical message remains clear: physical activity, at any hour, is a cornerstone intervention in managing type 2 diabetes. However, optimizing timing could offer an additional tool for improving metabolic outcomes.
Study
Schmidt Kjølner Hansen S, Zierath JR, Wallberg-Henriksson H. Exercise timing and circadian regulation of metabolism in type 2 diabetes. Trends Endocrinol Metab. Published online March 19, 2026. doi:10.1016/j.tem.2026.01.015
Abbonati a Karla Miller
