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CGM Motivates Prediabetes and Type 2 Patients to Increase Physical Activity

Using a continuous glucose monitor helps those with prediabetes and type 2 diabetes to self-regulate their exercise.

When CGMs first came out they were not recommended, not very accurate and had a lot of problems. But just recently, assistant Professor Mary Jung, a researcher at the University of British Columbia, Canada conducted a small eight-week pilot study that taught people with type 2 diabetes and prediabetes to self-monitor and self-regulate their exercise.

Although exercise is an important treatment strategy to improve long-term glycemic control in people with type 2 diabetes, the impact of exercise on 24-hour glycemic control has remained largely unexplored. The introduction of continuous glucose monitoring (CGM) several years ago enabled researchers to investigate the impact of exercise strategies on 24-hour glycemic control. Such unique information on the glucoregulatory properties of exercise can lead to more effective exercise intervention programs to prevent and treat type 2 diabetes.

The participants were divided into two groups: the first group was provided a CGM and educated about goal-setting, self-monitoring and how exercise affects BG levels. The second group was given general healthcare tips, including foot care and stress management.

Jung reported that the CGM-wearing group was vigilant about sticking to an exercise program during the study period. They were still found to be exercising one month after the study period and were significantly more likely to sign up for exercise programs compared to the non-CGM group.

Jung added that, “We found those receiving self-regulatory skills training and provided with the CGMs were more confident in their ability to stick with exercise, were self-monitoring more, and had built exercise goals into their lifestyle.”

Before the introduction of the CGM technique, the acute and short-term effects of exercise could only be monitored in a laboratory setting by means of frequent blood sampling. Although interesting, laboratory-based experiments do not provide an answer to the question of whether exercise reduces blood glucose excursions in a real-life setting. For this reason, researchers started using blinded CGM to investigate the impact of acute exercise on 24-hour glycemic control under free-living conditions.

Given the unique information on daily blood glucose homeostasis provided by CGM, this method has become increasingly popular as a means to investigate the impact of exercise strategies on 24-hour glycemic control in patients with type 2 diabetes. A recent meta-analysis of CGM studies indicated that exercise reduces postprandial blood glucose concentrations, whereas no effect was seen on fasting blood glucose concentrations.

These findings support the view that the application of CGM under free-living conditions represents a more appropriate method to assess the impact of various treatment strategies on glycemic control than the standard laboratory-based blood glucose measurements. Another advantage of the CGM technique is that the intervention or monitoring periods can be kept relatively short. This allows for crossover intervention studies with the possibility to standardize or control for patients’ medication, diet, and physical activity patterns.

By application of the CGM technique, it was shown that, for a fixed volume of exercise, short exercise sessions performed on a daily basis (30 minutes daily) offer no additional benefits for glycemic control compared to prolonged bouts of exercise performed less frequently (60 minutes every other day). This finding implies that the total volume of exercise is more important than the frequency with which exercise sessions are being performed. In line with this view, a dose-response relationship has been observed between the volume of endurance exercise training and subsequent improvements in insulin sensitivity and glycemic control, irrespective of the frequency at which exercise sessions were being performed.

Although exercise is an important treatment strategy to improve long-term glycemic control in people with type 2 diabetes, the impact of exercise on 24-hour glycemic control has remained largely unexplored. The introduction of CGM several years ago enabled researchers to assess the impact of exercise strategies on 24-hour glycemic control. The use of this technology demonstrated that a single bout of exercise reduces the prevalence of hyperglycemia throughout the subsequent 24-hour period. In this regard, resistance and endurance exercise appear to be equally effective in improving 24-hour glycemic control.

Moreover, recent data from CGM studies suggest that the volume of exercise, also referred to as the exercise dose, is the main determinant of exercise-induced improvements in glycemic control. Thus, when designing exercise programs, the initial focus should be on the selection of an appropriate volume of exercise. After selecting an appropriate volume of exercise, the other exercise characteristics (i.e., frequency, duration, and intensity) can be used to tailor the exercise program to match patients’ preferences and functional abilities.

Practice Pearls:

  • The introduction of CGM enabled researchers to assess the impact of exercise strategies on 24-hour glycemic control.
  • The use of CGM technology demonstrated that a single bout of exercise reduces the prevalence of hyperglycemia throughout the subsequent 24-hour period.
  • Resistance and endurance exercise appear to be equally effective in improving 24-hour glycemic control.

Diabetes Technology and Therapeutics journal: May 2016

“Exercise Strategies to Optimize Glycemic Control in Type 2 Diabetes: A Continuing Glucose Monitoring Perspective,” Diabetes Spectr. 2015 Jan; 28(1): 24–31. doi:  10.2337/diaspect.28.1.24