Exercise provides many metabolic benefits for people with type 2 diabetes; nevertheless, the ability to switch substrate oxidation from fat to carbohydrate and back, known as metabolic flexibility (MetFlex), in response to prolonged exercise training has not been thoroughly explored.

Purpose: The goal of this analyses was to investigate changes in MetFlex after an exercise intervention. We enrolled healthy sedentary participants with obesity (HSO) and participants with type 2 diabetes (T2DM) in a 10-week aerobic exercise intervention.

Methods: Seventeen participants with T2DM (8 females; 52.9 years; BMI= 36.9 kg/m2 and 9 males; 48.8 years; BMI= 33.3 kg/m2) and seven HSO (5 females; 44.8 years, BMI= 37.6 kg/m2 and 2 males; 46.5 years, BMI= 36.2 kg/m2) completed the intervention. MetFlex was assessed as the respiratory quotient (RQ) kinetic response after ingesting a standard high CHO breakfast during a 24-h energy expenditure measurement in a whole-room respiratory chamber. Briefly, the kinetics between the lowest RQ and highest RQ points were analyzed by a simple linear regression between time (1-minute resolution) and RQ units (RQUnits). Individual data were time-aligned and averaged for each group and moments (PRE and POST intervention), then slopes and intercepts for T2DM vs. HSO groups and PRE vs. POST were compared using a multiple regression model.

Results: At PRE-intervention, HSO group had a significantly lower intercept than T2DM (HSO=0.737 vs. T2DM=0.705; P<0.001) and slower RQ kinetics as demonstrated by a greater slope (HSO=0.00448 RQUnits/min vs. T2DM=0.00332 RQUnits/min; F=18.1, P=0.001). After the exercise intervention only T2DM significantly increased their slope (POST= 0.003944 RQUnits/min; F=6.47, P=0.013).

Conclusions: Our results indicate that participants with diabetes significantly improve MetFlex following a prolonged aerobic exercise intervention.


E.A. Carnero: None. C.P. Bock: None. N. Stephens: None. R.E. Pratley: Other Relationship; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eisai Inc., GlaxoSmithKline plc., Janssen Pharmaceuticals, Inc., Lexicon Pharmaceuticals, Inc., Ligand Pharmaceuticals, Inc., Eli Lilly and Company, Merck & Co., Inc., Novo Nordisk Inc., Pfizer Inc., Sanofi-Aventis, Takeda Development Center Americas, Inc.. S.R. Smith: None. L.M. Sparks: None.

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