| Objective: Glycemic fluctuations and postprandial hyperglycemia are significant cardiovascular disease risk factors for patients with type 2 diabetes.Therefore,better management of glycemic fluctuations and postprandial hyperglycemia is an important target in type 2 diabetes treatment.Considering the insulin sensitivity may increase by exercise particularly in patients with type 2 diabetes,little has been done in studying glycemic variation during exercise in patients with insulin.Many studies have demonstrated that exercising during the postprandial period has been shown to cause acute reductions in postprandial blood glucose.However,post-dinner exercise has not always been differentially investigated.The aim of our study was to investigate effectiveness of moderate-intensity exercise on the glycemic response in a study population of Chinese patients with type 2 diabetes,using the continuous glucose monitoring(CGM).Methods: In the first section,the patients with type 2 diabetes,who were treated with a continuous subcutaneous insulin infusion(CSII)therapy,were enrolled in the observational study.Patients were asked to complete 30 min aerobic exercise for at least one time during CGM.The patients were divided into effective and ineffective group by incremental glucose area under curve from 0 to 60 min after exercise(AUC0-60min).Linear regression and Pearson analysis were performed to identify the parameters that correlate with the change values in term of the incremental AUC of blood glucose during and after exercise.Then,the impact of time points on blood glucose in exercise was explored.In the second section,the two randomized,crossover,self-controlled pilot studies were conducted in inactive patients with type 2 diabetes without serious complications or use of exogenous insulin.The first study involved patients with type 2 diabetes who participated in post-dinner exercise,using their non-exercise condition as a control.For the nonexercise control days,patients pursued normal daily activities but refrained from unusual strenuous physical activity.On the exercise days,participants walked on a treadmill for 20 minutes at 30 min after dinner.In the second study,the participants completed two randomly ordered exercise protocols(brisk walking for 30 min at 30 min or 60 min after dinner on the exercise day)spaced 1 week apart.The interstitial glucose level was monitored using a CGM for all the participants,who maintained a standardized diet with routine medications.Results: In the first section,the study population consisted of 267 participants,who completed a total of 776 times of aerobic exercises.We found that blood glucose decreased fastest in the first 60 min of exercise in the third study.Pre-exercise blood glucose(PEBG)was negatively correlated with AUC0-60min(P<0.001)and incremental AUC of blood glucose ≤4.4 mmol/L(P=0.034).PEBG was significantly higher in effective group than in ineffective group(P<0.001).The Δglucose AUC0-60min(AUC0-60 min during the same time in another day that did not exercise minus AUC0-60 min during exercise)during post-dinner was significantly higher than that during pre-lunch,post-lunch and pre-dinner(P<0.05 for all).In the second section,29 patients with uncomplicated type 2 diabetes treated with diet and/or a variety of oral glucose lowering medications volunteered for the first study,and the second study was conducted in 15 participants.In the first study,significant glucose reductions in the 2-h postprandial glucose spike(P=0.04),2-h postprandial peak glucose(P=0.02),and 2-h postprandial mean glucose(P=0.04)levels were detected on the exercise day compared to those under the control condition.Significant differences were not observed in dinner 2-h postprandial glucose area under the curve(AUC).However,the glucose AUC during 1-hour post-exercise was lower with exercise than under the control condition(P=0.01).The 12-hour standard deviation(SD)of blood glucose and the coefficient variation(CV)of glucose were significantly lower in the exercise day compared to the control day,although the 12-hour mean amplitude of glycemic excursions(MAGE)did not reach statistical significance.No nocturnal hypoglycemia subsequently occurred on the exercise day.In the second study,no significant differences were found between postprandial 30 min exercise group and postprandial 60 min exercise group in terms of 2-h postprandial mean glucose,peak glucose,glucose AUC,or in MBG,CV of glucose and MAGE during the 12-h period after dinner.No nocturnal hypoglycemia occurred in the participants after exercise at 30 or 60 min after dinner.However,significant reductions in the 2-h postprandial glucose levels were detected after exercise at 60 min after dinner as compared to exercise at 30 min(P=0.04).Conclusions: PEBG is positively correlated with efficacy of aerobic exercise in type 2 diabetes who treated with CSII therapy.Aerobic exercise will not worsen hyperglycemia when the PEBG >16.7 mmol/L.Post-dinner exercise decreases the blood glucose better than other periods of the day.A short session of moderate-intensity post-dinner exercise can improve postprandial hyperglycemia and glycemic excursions in patients with type 2 diabetes,with no potential hypoglycemia risk at a later period.The timing(30 min vs 60 min after dinner)of moderate exercises for 30 min does not produce significant difference in the improvement of postprandial hyperglycemia in type 2 diabetic patients,and both exercise protocols are safe without a potential risk of hypoglycemia.Nevertheless,exercise at 60 min after dinner can be more effective to lower 2-h postprandial glucose,while exercise at 30 min after dinner might be safer for patients with a high risk of postprandial hypoglycemia. |
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