BONE AND MUSCLE STRENGTH IN CHILDREN WITH TYPE 1 DIABETES

Abstract

Introduction: Bone fragility in children and youth with Type 1 Diabetes (DM1) may relate to weaker bones and muscles, but the evidence is limited. The objectives of my thesis were (1) to compare bone and muscle properties and strength between children with and without DM1, and (2) to explore if muscle outcomes are mediators explaining the bone differences between children with and without DM1. Methods: I included 25 children with DM1 and 168 typically developing children and youth (age 6-15yrs) in my thesis. Their bone properties and muscle size were measured using peripheral quantitative computed tomography (pQCT). Muscle force was assessed using neuromuscular performance measures, including maximal grip force, push-up, countermovement and long jump tests. I compared bone and muscle properties and strength between children with and without DM1 using MANCOVA followed by pairwise comparisons (1st objective). I added muscle size and force into regression models as possible mediators to assess if muscle outcomes are mediators helping explain the potential bone difference between children with and without DM1 (2nd objective). Results: There were group differences in bone and muscle properties and strength (p<.05). Cortical area was 7% and 10% lower and density was 8% higher and 5% higher at radius and tibia shafts, respectively, in children with DM1. Children with DM1 also had 6% lower cortical content at tibia shaft. There was no difference at the distal radius or tibia bone properties and strength between groups. Children with DM1 had 12% higher maximal push-up force. Lower leg muscle area was a mediator for tibia shaft cortical bone content and area difference between children with and without DM1. Conclusion: Children with DM1 had smaller cortical area but higher density at the radius and tibia shafts. Lower leg muscle area was a mediator explaining the lower tibia shaft cortical bone content and area difference between groups.