Evening Exercise Shows Arterial Stiffness Signal in Type 2 Diabetes
Key Takeaways
- In older adults with type 2 diabetes in a Shanghai exercise trial, both schedules improved FMD and lowered baPWV, SBP, and MAP from baseline.
- An exploratory direct comparison found a significantly greater baPWV reduction with evening than morning exercise.
- NO increased significantly within the evening-exercise arm but not the morning arm; the direct comparison between schedules was not statistically significant.
In a randomized exercise-timing trial, investigators in Shanghai assigned 66 adults aged 60–75 with type 2 diabetes to morning exercise, evening exercise, or control (22 per arm). Participants had not met recommended activity levels in the preceding three months. The final analysis included 58 participants: 20 morning, 19 evening, and 19 control. Both exercise arms completed the same remotely supervised, moderate-intensity aerobic and elastic-band resistance program over 12 weeks, with three 70-minute sessions weekly at 09:00–10:10 or 19:00–20:10. Controls maintained their usual lifestyle and received weekly online health education without structured exercise.
Ultrasound-assessed flow-mediated vasodilation (FMD) was the primary vascular outcome used for sample-size planning. Investigators also measured brachial-ankle pulse wave velocity (baPWV), an arterial-stiffness measure, systolic blood pressure (SBP), mean arterial pressure (MAP), and plasma nitric oxide (NO). Assessments occurred at baseline and after training, with exercise participants tested 48–72 hours after their final session. A principal three-arm group-by-time analysis was supplemented by an exploratory direct exercise-arm comparison. The final analysis required complete measurements, unchanged medication, and at least 80% session completion; missing data were not imputed.
Both exercise groups improved FMD and reduced baPWV, SBP, and MAP from their own baselines. Neither these within-arm changes nor the principal three-arm interactions establish an advantage for either exercise time. In the exploratory direct comparison, baPWV fell by −221.1 cm/s with evening exercise versus −89.2 cm/s with morning exercise (group × time p = 0.034). Controls showed no comparable decline.
At follow-up, FMD and plasma NO were significantly higher and MAP significantly lower in the evening arm than in controls. NO rose significantly within the evening arm but not the morning arm; the direct timing interaction was not statistically significant (p = 0.051). Direct comparisons of FMD and blood-pressure changes likewise found no significant schedule differences. Attendance was high in both exercise arms. Investigators reported no exercise-related adverse events.
The direct schedule comparisons were supplementary and exploratory in a small analyzed group. A significant change within one arm but not the other does not itself establish a between-arm difference. Six participants discontinued for health or family reasons; two controls were omitted after lifestyle or medication changes. Outcomes were short-term vascular surrogates, not cardiovascular events or sustained effects after training. The investigators noted the absence of an afternoon arm, an imbalance in baseline lipid-lowering medication use, and incomplete control or monitoring of diet, sleep, outside activity, and medication timing. Shear rate was not measured during FMD testing because simultaneous post-deflation diameter and velocity recording was unavailable.
The investigators concluded that both schedules were associated with vascular improvements and that the exploratory arterial-stiffness comparison favored evening exercise. The findings do not establish an optimal exercise time or demonstrate a direct timing difference for FMD, NO, or blood pressure.
Clinician Questions
Which older adults with type 2 diabetes were excluded from the morning-versus-evening exercise trial?
The trial of combined exercise in adults aged 60–75 with type 2 diabetes excluded people with serious cardiovascular disease, a history of stroke, conditions restricting exercise participation, or severe diabetes complications that could compromise exercise safety. Cancer and psychiatric disorders were also exclusion criteria; the findings do not extend to these excluded groups.
How was plasma nitric oxide measured in older adults with type 2 diabetes who exercised in the morning or evening?
Investigators in the morning-versus-evening combined-exercise trial assessed plasma NO indirectly through spectrophotometric measurement of its nitrite and nitrate metabolites. This was a metabolite-based plasma measure, not a direct NO assay.
Recommended Reading
- For more on lifestyle strategies in diabetes: Rethinking Diabetes Care: Key Data from Incorporating Lifestyle Modifications
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