Could Age, Sex and Physical Fitness Affect Blood Glucose Responses to Exercise in Type 1 Diabetes?

Abstract

Closed-loop systems for patients with type 1 diabetes are progressing rapidly. Despite these advances, current systems may struggle in dealing with the acute stress of exercise. Algorithms to predict exercise-induced blood glucose changes in current systems are mostly derived from data involving relatively young, fit males. Little is known about the magnitude of confounding variables such as sex, age, and fitness level—underlying, uncontrollable factors that might influence blood glucose control during exercise. Sex-related differences in hormonal responses to physical exercise exist in studies involving individuals without diabetes, and result in altered fuel metabolism during exercise. Increasing age is associated with attenuated catecholamine responses and lower carbohydrate oxidation during activity. Furthermore, higher fitness levels can alter hormonal and fuel selection responses to exercise. Compounding the limited research on these factors in the metabolic response to exercise in type 1 diabetes is a limited understanding of how these variables affect blood glucose levels during different types, timing and intensities of activity in individuals with type 1 diabetes (T1D). Thus, there is currently insufficient information to model a closed-loop system that can predict them accurately and consistently prevent hypoglycemia. Further, studies involving both sexes, along with a range of ages and fitness levels, are needed to create a closed-loop system that will be more precise in regulating blood glucose during exercise in a wide variety of individuals with T1D.

Improving Clinical Outcomes in Newly Diagnosed Pediatric Type 1 Diabetes: Teamwork, Targets, Technology, and Tight Control—The 4T Study

“…For youth with T1D, many factors need to be taken into consideration before engaging in physical activity such as starting glucose level, timing and intensity of activity, insulin dosing, carbohydrate supplementation, exercise time of day, individual fitness, and prior episodes of hypoglycemia ( 69 – 71 ). It is essential for clinicians and health-care practitioners to encourage regular physical activity; however, this requires a more in-depth understanding of strategies to better manage glycemia during exercise ( 66 , 70 ).…”

Exercise‐induced hypoglycaemia in type 1 diabetes

“…Clearly, more work is required to dissect these differences. It might be that sex differences are amplified and dependent on the type of exercise, and the previously reported difference in fuel utilization by men (more carbohydrate) and women (more fat) could explain these differences (Hedrington & Davis, ; Yardley, Brockman, & Bracken, ).…”

<p>The Athlete with Type 1 Diabetes: Transition from Case Reports to General Therapy Recommendations</p>

“…To date, this publication offers the most detailed exercise safety guidelines available to the athlete or active individual with type 1 diabetes, including advice for insulin dosage management, dietary management, and hydration for specific levels of blood glucose, relative to different intensities and durations of exercise. However, it should still be noted that most of the studies on which this advice is based were performed on young, fit, males, and do not take into account potential age-63 and sex-related63,64 differences in exercise responses. As such, it is still advisable to individually tailor exercise and physical activity recommendations to the individual.…”