Insulin Resistance and Diabetes Mellitus in Contemporary Cardiac Rehabilitation.

Abstract

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). 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%). 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. 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.