Background: Type 2 diabetes mellitus (T2DM) is associated with a higher risk for heart failure (HF). The impact of a lifestyle intervention and changes in cardiorespiratory fitness (CRF) and body mass index on risk for HF is not well established.
Methods: Participants from the Look AHEAD trial (Action for Health in Diabetes) without prevalent HF were included. Time-to-event analyses were used to compare the risk of incident HF between the intensive lifestyle intervention and diabetes support and education groups. The associations of baseline measures of CRF estimated from a maximal treadmill test, body mass index, and longitudinal changes in these parameters with risk of HF were evaluated with multivariable adjusted Cox models.
Results: Among the 5109 trial participants, there was no significant difference in the risk of incident HF (n=257) between the intensive lifestyle intervention and the diabetes support and education groups (hazard ratio, 0.96 [95% CI, 0.75-1.23]) over a median follow-up of 12.4 years. In the most adjusted Cox models, the risk of HF was 39% and 62% lower among moderate fit (tertile 2: hazard ratio, 0.61 [95% CI, 0.44-0.83]) and high fit (tertile 3: hazard ratio, 0.38 [95% CI, 0.24-0.59]) groups, respectively (referent group: low fit, tertile 1). Among HF subtypes, after adjustment for traditional cardiovascular risk factors and interval incidence of myocardial infarction, baseline CRF was not significantly associated with risk of incident HF with reduced ejection fraction. In contrast, the risk of incident HF with preserved ejection fraction was 40% lower in the moderate fit group and 77% lower in the high fit group. Baseline body mass index also was not associated with risk of incident HF, HF with preserved ejection fraction, or HF with reduced ejection fraction after adjustment for CRF and traditional cardiovascular risk factors. Among participants with repeat CRF assessments (n=3902), improvements in CRF and weight loss over a 4-year follow-up were significantly associated with lower risk of HF (hazard ratio per 10% increase in CRF, 0.90 [95% CI, 0.82-0.99]; per 10% decrease in body mass index, 0.80 [95% CI, 0.69-0.94]).
Conclusions: Among participants with type 2 diabetes mellitus in the Look AHEAD trial, the intensive lifestyle intervention did not appear to modify the risk of HF. Higher baseline CRF and sustained improvements in CRF and weight loss were associated with lower risk of HF. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT00017953.
Keywords: body mass index; cardiorespiratory fitness; diabetes mellitus, type 2; heart failure; obesity; overweight; risk.