Endocrine Abstracts

Introduction: In patients with type 1 diabetes, exercise has not consistently been shown to improve glycemic control, as measured using HbA1c levels. Participation in competitive sports may even worsen glycaemic control. Free radicals and oxidative stress markers are known to increase during acute exercise in parallel to decreased circulating antioxidant concentrations. We aimed to analyze the effects of chronic and acute exercise on circulating HbA1c and fructosamine levels.

Design: We evaluated six patients (five men and one woman). Their mean age was 41.8 (range: 22–49). Their mean diabetes duration was 11.3 years (range: 5–20). All of them were under intensive treatment before the study (four with MID and two with ISCI). Prior to the training period, they usually ran 35 km 3 days every week, which increased to 70–80 km 5 days/week during the training period. We analyzed their HbA1c and fructosamine levels before and after the training period and also before and after running a half-marathon (20 km).

Results: After eight months training, mean HbA1c decreased from 7.80% (95% CI 6.80–8.79) to 7.55% (95% CI: 6.52–8.57) (P 0.13) and mean fructosamine levels decreased from 370.5 μmol/l (95% CI 311.87–429.12) to 350 μmol/l (95% CI 292.97–407.02) (P 0.075). Paradoxically, after acute exercise, mean HbA1c increased from 7.53% (95% CI 6.54–8.52) to 7.61% (95% CI 6.61–8.51) (P 0.025) in parallel to raised fructosamine levels from 348.3 μmol/l (95% CI 298.1–398.5) to 363.8 μmol/l (95% CI 318.3–409.2) (P 0.046). HbA1c was determined using HPLC (reference range: 4.1–6.2%, Intra and interassay coefficients of variation (CV) were 0.7 and 0.74% respectively). Fructosamine was determined by spectrophotometer (normal values ≤285 μmol/l. Intra and interassay CV were 1.7 and 3.9% respectively.

Conclusion: Acute exercise should be taken into account as one of the factors influencing HbA1c variability in a short time.