Insulin Resistance and Diabetes Mellitus in Contemporary Cardiac Rehabilitation.

Purpose: The goal of this study was to determine the prevalence of insulin resistance (IR) and type 2 diabetes mellitus (T2DM) in contemporary cardiac rehabilitation (CR) and to compare clinical responses in CR between these subsets of patients with coronary heart disease (CHD).
Methods: The study cohort included 818 patients enrolled in CR and separated into 3 groups: (1) individuals with normal hemoglobin A1c (HbA1c) (NoIR: HbA1c < 5.7%); (2) individuals with IR (IR: HbA1c ≥ 5.7 to <6.5%); (3) and individuals with T2DM (HbA1c ≥ 6.5%).
Results: The combined prevalence of IR (44%) and T2DM (23%) was 67%, which paralleled the prevalence of metabolic syndrome (MetSyn), present in 65% of patients. Women had a higher prevalence of IR and MetSyn than men (73% vs 64%, 72% vs. 63%, respectively) and a greater percentage with an elevated waist circumference (71% vs 60%) (all P < .05). All 3 groups experienced decreases in body weight (NoIR = -2.3 ± 4.0, IR = -1.7 ± 4.0, T2DM = -1.0 ± 4.2 kg) and increases in maximal metabolic equivalents (METs) at exercise testing (NoIR = +2.2 ± 2.5 vs IR = +2.1 ± 2.8 vs T2DM = +1.3 ± 2.3) (all P < .05). Individuals with NoIR achieved greater improvements in weight, body mass index, and METs than patients with T2DM (all P < .05). Selected individuals who participated in a 4-session behavioral weight-loss program lost more than twice the weight as nonparticipants.
Conclusions: The combined prevalence of IR and T2DM in patients with CHD enrolled in CR was remarkably high (67%). To reverse the deleterious consequences of IR and T2DM, targeted interventions involving exercise and weight loss need to be a central focus of CR programming.