Do those with type 1 diabetes need more exercise to maintain skeletal muscle health?

Abstract

Figure 1. Recent studies have reported that despite similarities in baseline physical activity, those with type 1 diabetes (T1D) exhibit many alterations to skeletal muscle health The latest study by Minnock and colleagues extends the field of work by demonstrating that while exercise training in those with T1D was effective in reducing glycaemic fluctuations and hypoglycaemic events, the degree of improvements in skeletal muscle health metrics is reduced compared to those without the disease. This work highlights the limitations of current exercise guidelines and suggests that future studies are necessary to define the exercise requirements necessary to achieve optimal muscle health and maximize the physical and metabolic capacities of those with T1D. key determinant of whole-body insulin sensitivity. Importantly, these metabolic contributions to whole body health, when dysregulated (dysglycaemia, dyslipidaemia, insulin resistance), have been identified as primary contributors to the development of complications in those with type 1 diabetes (T1D). Thus, it is reasonable to consider that impairments to the health of skeletal muscle would expedite the progression of T1D complications. Moreover, increasing evidence is emerging that skeletal muscle health is a well-established determinant of quality of life and survival (McLeod et al. 2016). Several recent human studies have demonstrated that the skeletal muscles of those with T1D exhibit numerous deficits, relative to matched non-T1D subjects, leading to the proposal that muscles of those with T1D exhibit accelerated ageing. These changes include decreases in strength (Dial et al. 2021), changes in myofibre morphology and size (Dial et al. 2021), impaired mitochondrial function (Monaco et al. 2018, 2021), ultrastructural abnormalities in mitochondria (Monaco et al. 2018), increased mitochondrial ROS emission (Monaco et al. 2018), and alterations to skeletal muscle repair following exercise (Dial et al. 2021). Notably, many of these alterations in muscle health were sexually dimorphic, present across a variety of ages, and evident despite similarities in self-reported physical activity levels with non-T1D matched subjects. Despite the aforementioned differences in muscle health, persons with T1D are able to effectively undertake exercise training. However, what has yet to be fully examined is whether exercise training is capable of eliciting the same skeletal muscle adaptations in those with T1D as it is in their non-T1D matched counterparts. This makes the publication from Minnock and colleagues (2022) in this issue of The Journal of Physiology a valuable contribution to the study of diabetic myopathy and exercise training (Fig. 1). Using males and females with and without T1D, the authors had subjects undertake 12weeks of combined exercise training with preand post-training measurements including systemic measures (body composition, aerobic capacity, muscle strength), glycaemic variability and muscle biopsies (markers of mitochondrial function, inflammation, growth and remodelling). As expected, exercise training did have beneficial effects on glycaemic control in those with T1D. The training intervention also improved aerobic capacity and muscle strength in both groups, but to a lesser