Metabolic and physiological responses to graded exercise testing in individuals with type 1 diabetes using insulin pump therapy

Abstract

Aims: To profile acute glycaemic dynamics during graded exercise testing (GXT) and explore the influence of glycaemic indicators on the physiological responses to GXT in adults with type 1 diabetes using insulin pump therapy. Methods: This was a retrospective analysis of pooled data from four clinical trials with identical GXT protocols. Data were obtained from 45 adults with type 1 diabetes using insulin pumps [(30 females); haemoglobin A1c 59.5 ± 0.5 mmol/mol (7.6 ± 1.0%); age 49.7 ± 13.0 years; diabetes duration 31.2 ± 13.5 years; V̇O2peak 29.5 ± 8.0 ml/min/kg]. Integrated cardiopulmonary variables were collected continuously via spiroergometry. Plasma glucose was obtained every 3 min during GXT as well as the point of volitional exhaustion. Data were assessed via general linear modelling techniques with age and gender adjustment. Significance was accepted at p ≤.05. Results: Despite increasing duration and intensity, plasma glucose concentrations remained similar to rest values (8.8 ± 2.3 mmol/L) throughout exercise (p =.419) with an overall change of +0.3 ± 1.1 mmol/L. Starting glycaemia bore no influence on subsequent GXT responses. Per 1% increment in haemoglobin A1c there was an associated decrease in V̇O2peak of 3.8 ml/min/kg (p