Reproducibility of Glucose Fluctuations Induced by Moderate Intensity Cycling Exercise in Persons with Type 1 Diabetes

Abstract

Aims. The purpose was to assess the reproducibility of glucose changes during three sessions of standardized moderate intensity continuous training of cycling on an individual level in people with type 1 diabetes. Methods. Twelve adults (six females) with type 1 diabetes performed three test sessions on an ergometer bicycle (30 min, 67% of predicted heart rate) on three different days. The participants were 36.5 (26.6-45.5) (median, IQR) years old, and their HbA1c was 65 ± 15 mmol/mol ( mean ± SD ). Two hours before the tests, the participants had a standard meal. Interstitial glucose (IG) and capillary glucose (CG) were measured using an iPro2 Medtronic continuous glucose monitor and the Bayer Contour XT-device, respectively. Prior to the test sessions, resting heart rate was measured using a digital blood pressure monitor to estimate the desired intensity of the exercise. Results. The average within-participant relationship between the average slope in glucose during sessions 2 and 1 was in IG -0.29 (95% CI -1.11; 0.58) and in CG -0.04 (-0.68; 0.77). Between sessions 3 and 2, IG is 0.18 (-0.27; 0.64) and in CG 0.13 (-0.25; 0.55). Between sessions 3 and 1, IG was 0.06 (-0.57; 0.71) and in CG 0.06 (-0.39; 0.52). The results indicate low reproducibility at participant levels and remained unchanged after adjustment for baseline glucose values. Conclusion. On an individual level, the glucose declines during three standardized sessions of PA were not associated with identical responses of the measured IG and CG levels. An overall anticipated decline of glucose concentrations was found in the moderate intensity cycling sessions. This highlights the importance of regular CG measurements during and after physical activity and awareness towards potential exercise-induced hypoglycemia in persons with type 1 diabetes.

Are There Interindividual Responses of Cardiovascular Disease Risk Markers to Acute Exercise? A Replicate Crossover Trial

“…Previous research has sought to quantify the reproducibility of postprandial CVD risk marker responses to single meals and/or acute exercise exposures (11)(12)(13)(14)(15)52,53). Specifically, these studies provide evidence that meal-stimulated responses are reproducible when postprandial assessments are repeated on at least two occasions for TAG (11,12,14,15) and BP (13).…”

“…However, greater variation in the postprandial TAG response emerged when an identical bout of exercise was undertaken immediately before meal ingestion (Spearmen's ranked correlation coefficient, 0.42) (12). Similarly, poor reproducibility has also been described for postprandial glucose responses to three identical bouts of cycling (52), along with brachial artery PWV in response to two identical cycling tests (53). Unfortunately, a limitation of previous studies when exploring exercise-specific responses is the failure to account for random within-subject variability of the measurement, which can be determined by measuring outcomes in repeated control and intervention condition arms, and subsequently adjusting the intervention response for the natural fluctuations that occur over time (16,21,25).…”

Physical Activity, Dietary Patterns, and Glycemic Management in Active Individuals with Type 1 Diabetes: An Online Survey

“…Being physically active with T1D increases an individual's risk of activity-related hypoglycemia [77][78][79] and hyperglycemia [80,81], and fear of activity-related hypoglycemia has often been a deterrent of regular participation for insulin users of all ages [82,83]. Conversely, since all of our participants were engaging in regular physical activity, they likely had already adapted their diabetes management strategies to better manage their glycemic variations while minimizing any fear of hypoglycemia associated with being active; in fact, out of 220 participants, only 10 reported A1C values of 8% or higher and only two of those were above 9%.…”

“…Active individuals completing our online survey frequently expressed frustrations with maintaining glycemic balance while doing a variety of physical activities under free-living conditions [55]. A recent study conducted on 12 adults with T1D reported that three identical cycling sessions completed on separate days under controlled conditions resulted in varying values for glucose measured either with a finger-stick (capillary blood) blood glucose monitor or a CGM device, even though glucose declined in all three trials [78]; these results indicated low reproducibility at the participant level and remained unchanged after adjustment for baseline glucose values. Likewise, in adolescents with T1D, while greater intrasubject reliability and repeatability of blood glucose responses to prolonged exercise was shown to be possible, this result occurred only when pre-exercise meal, exercise, and insulin regimens were kept constant [84], which is not always feasible in real life.…”

New Contributions Towards Meal and Exercise Announcement-Free Artificial Pancreas Systems

“…Nevertheless, depending on the type of exercise, intensity, duration, or timing, exercise can even cause a glucose rise (Ruegemer et al 1990;Moser et al 2020), which might require a different strategy to compensate for it. The simulator neither accounted for the high intrapatient variability in the exercise (Notkin et al 2021). Similarly, the simulator considers that meals are composed of carbohydrates only.…”