title: Does metformin modify the effect on glycaemic control of aerobic exercise, resistance exercise or both?
abstract: OBJECTIVE
  Some previous studies suggested that metformin might attenuate the effects of exercise on glycaemia or fitness. We therefore examined whether metformin use influenced changes in glycaemic control, fitness, body weight or waist circumference resulting from aerobic and/or resistance training in people with type 2 diabetes participating in an exercise intervention trial.
  
  
  METHODS
  After a 4 week run-in period, participants from the Diabetes Aerobic and Resistance Exercise (DARE) trial were randomly assigned to 22 weeks of aerobic training alone, resistance training alone, combined aerobic and resistance exercise training or a waiting-list control group. Of the 251 randomised, 143 participants reported using metformin throughout the entire study period and 82 reported not using metformin at all.
  
  
  RESULTS
  Compared with control, aerobic training led to a significant reduction in HbA1c in the metformin users (-0.57%, 95% CI -1.05, -0.10; -6.3 mmol/mol, 95% CI -11.5, -1.1) but not in the non-metformin users (-0.17, 95% CI -0.78, 0.43; -1.9 mmol/mol, 95% CI -8.5, 4.7). However, there were no significant differences in the changes in HbA1c (or fasting glucose) between metformin users and non-users in any of the exercise groups compared with control (p> 0.32 for all metformin by group by time interactions). Similarly, metformin did not affect changes in indicators of aerobic fitness, strength and body weight or waist circumference (p ≥ 0.15 for all metformin by group by time interactions).
  
  
  CONCLUSIONS
  Contrary to our hypothesis and to previous short-term studies, metformin did not significantly attenuate the benefits of exercise on glycaemic control or fitness.
authors: Faculty of Physical Education and Recreation, 1-002 Li Ka Shing Centre for Health Research Innovation, University of Alberta, Edmonton, AB, Canada, T6G 2E1, nboule@ualberta.ca.
authors: Normand G
authors: NG
authors: Boulé
authors: Glen P
authors: GP
authors: Kenny
authors: Joanie
authors: J
authors: Larose
authors: Farah
authors: F
authors: Khandwala
authors: Nicholas
authors: N
authors: Kuzik
authors: Ronald J
authors: RJ
authors: Sigal
mesh_terms: D000328:Adult; D000368:Aged; D001786:Blood Glucose / Q000187:drug effects*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006442:Glycated Hemoglobin / Q000378:metabolism; D006801:Humans; D008297:Male; D008687:Metformin / Q000627:therapeutic use*; D008875:Middle Aged; D055070:Resistance Training
chemical_list: D001786:Blood Glucose; D006442:Glycated Hemoglobin; D008687:Metformin
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