Fuel metabolism during exercise in euglycaemia and hyperglycaemia in patients with type 1 diabetes mellitus--a prospective single-blinded randomised crossover trial

• Published in: Diabetologia 2008-08, Vol.51 (8), p.1457-1465
• Main Authors: Jenni, S, Oetliker, C, Allemann, S, Ith, M, Tappy, L, Wuerth, S, Egger, A, Boesch, C, Schneiter, Ph, Diem, P, Christ, E, Stettler, C
• Format: Article
• Language: English
• Subjects: Adult; Aerobics; Age of Onset; Biological and medical sciences; Blood Glucose - metabolism; Carbohydrate oxidation; Carbohydrates; Carbon Dioxide - metabolism; Cross-Over Studies; Diabetes; Diabetes Mellitus, Type 1 - blood; Diabetes Mellitus, Type 1 - physiopathology; Diabetes. Impaired glucose tolerance; Endocrine pancreas. Apud cells (diseases); Endocrinopathies; Energy consumption; Energy Metabolism; Etiopathogenesis. Screening. Investigations. Target tissue resistance; Euglycaemia; Exercise; Glucose; Glucose clamp; Glucose Clamp Technique; Glucose turnover; Health care; Human Physiology; Humans; Hyperglycaemia; Hyperglycemia; Hyperglycemia - blood; Hyperglycemia - physiopathology; Insulin; Internal Medicine; Lipids; Lipids - blood; Magnetic resonance spectroscopy; Male; Maximum oxygen consumption; Medical sciences; Medicine; Medicine & Public Health; Metabolic Diseases; Metabolism; Oxidation; Oxygen Consumption; Physical fitness; Single-Blind Method; Spectrum analysis; Type 1 diabetes mellitus
• ISSN: 0012-186X; 1432-0428
• DOI: 10.1007/s00125-008-1045-5

Aims/hypothesis We assessed systemic and local muscle fuel metabolism during aerobic exercise in patients with type 1 diabetes at euglycaemia and hyperglycaemia with identical insulin levels. Methods This was a single-blinded randomised crossover study at a university diabetes unit in Switzerland. We studied seven physically active men with type 1 diabetes (mean ± SEM age 33.5 ± 2.4 years, diabetes duration 20.1 ± 3.6 years, HbA₁c 6.7 ± 0.2% and peak oxygen uptake [ [graphic removed] ] 50.3 ± 4.5 ml min⁻¹ kg⁻¹). Men were studied twice while cycling for 120 min at 55 to 60% of [graphic removed] , with a blood glucose level randomly set either at 5 or 11 mmol/l and identical insulinaemia. The participants were blinded to the glycaemic level; allocation concealment was by opaque, sealed envelopes. Magnetic resonance spectroscopy was used to quantify intramyocellular glycogen and lipids before and after exercise. Indirect calorimetry and measurement of stable isotopes and counter-regulatory hormones complemented the assessment of local and systemic fuel metabolism. Results The contribution of lipid oxidation to overall energy metabolism was higher in euglycaemia than in hyperglycaemia (49.4 ± 4.8 vs 30.6 ± 4.2%; p < 0.05). Carbohydrate oxidation accounted for 48.2 ± 4.7 and 66.6 ± 4.2% of total energy expenditure in euglycaemia and hyperglycaemia, respectively (p < 0.05). The level of intramyocellular glycogen before exercise was higher in hyperglycaemia than in euglycaemia (3.4 ± 0.3 vs 2.7 ± 0.2 arbitrary units [AU]; p < 0.05). Absolute glycogen consumption tended to be higher in hyperglycaemia than in euglycaemia (1.3 ± 0.3 vs 0.9 ± 0.1 AU). Cortisol and growth hormone increased more strongly in euglycaemia than in hyperglycaemia (levels at the end of exercise 634 ± 52 vs 501 ± 32 nmol/l and 15.5 ± 4.5 vs 7.4 ± 2.0 ng/ml, respectively; p < 0.05). Conclusions/interpretation Substrate oxidation in type 1 diabetic patients performing aerobic exercise in euglycaemia is similar to that in healthy individuals revealing a shift towards lipid oxidation during exercise. In hyperglycaemia fuel metabolism in these patients is dominated by carbohydrate oxidation. Intramyocellular glycogen was not spared in hyperglycaemia. Trial registration: ClinicalTrials.Gov NCT00325559 Funding: This study was supported by unrestricted grants from the Oetliker-Stiftung für Physiologie, from the Swiss Diabetes Foundation, from NovoNordisk, Switzerland, and from the Swiss National Scie