Effects of Exercise on Blood Glucose and Glycemic Variability in Type 2 Diabetic Patients with Dawn Phenomenon
A spontaneous increase of blood glucose or increase demand of insulin at dawn, despite reasonable blood glucose levels at night without hypoglycemia, is referred to as the dawn phenomenon (DP). Management of blood glucose levels is difficult in DP. The efficacy of oral hypoglycemic drugs, to control of DP, is weak. Therefore, Xin Zheng and colleagues (2020) conducted research entitled, “Effects of Exercise on Blood Glucose and Glycemic Variability in Type 2 Diabetic Patients with Dawn Phenomenon”, published in the journal “BioMedical Research International” to explore if exercise affects the dawn phenomenon. Below is the summary of the published article.
Objective
To investigate the effect of moderate-intensity aerobic training before breakfast on blood glucose level and glycemic variability in T2DM patients with dawn phenomenon.
Method
20 patients with T2DM were recruited. These patients experienced a difference of ≥20mg/dL between FBG and nocturnal blood glucose for 3 consecutive days. In these patients, DP was confirmed using CGM at the baseline. After collecting baseline measurements, CGM was re-installed in these patients for 3 days. Patients were instructed to track dawn blood glucose increase (ΔGlu = difference FBG and nocturnal blood glucose). To check glycemic variability, blood glucose levels pre- and post-exercise (30 mins walk on the treadmill) and pre and post breakfast were evaluated. They were also instructed to perform an exercise before breakfast.
Results
After initiation of exercise for 30 mins, the reduction was witnessed in FBG, ΔGlu, mean blood glucose, pre- and post-breakfast blood glucose. In comparison to before exercise, patients were in the time of range for a higher duration. Additionally, no effects were seen in nocturnal blood glucose. Furthermore, a decrease was observed in the indicators of glycemic variability (MAGE, LAGE< MODD, MPPGE, CV, SD) post-exercise. Out of 7 patients who were unable to meet the standard of glycemic variability, 3 patients were able to meet the standard. Also, 10 patients out of 20 patients were able to overcome DP.
Limitation
The authors have acknowledged that the mechanism behind the exercise-related improvement in DP is unclear. They encourage to conduct the study with a higher number of cases, along with observation of relevant hormones to determine improved understanding of the mechanism to resolve DP.