Previous research studies have identified that intensive lifestyle interventions were proven effective at lowering blood glucose levels. However, they were not established to reduce cardiovascular risk or mortality in patients with diabetes. A previous study called the Look AHEAD (Action for Health in Diabetes) trial did not find statistical significance between lifestyle interventions and the incidence of cardiovascular events. The Look AHEAD study was not powered enough to detect a difference and sustained glucose reduction was not achieved.
This cohort study wanted to assess whether lifestyle counseling is associated with lower cardiovascular risk and mortality in patients with diabetes. The study sought patients with uncontrolled diabetes (HbA1c of >= 7%) and aged 18 years or older that were seen by medical professionals at two academic medical centers. There were 3 stages in this study: a run-in period that began 12 months before entry, a two-year treatment assessment period that started on the date of entry, and the outcome ascertainment period which began at the end of the treatment assessment period and continued until the study was over. The frequency of lifestyle counseling and other treatment characteristics were assessed during hyperglycemic periods (HbA1c of 7% or more). Lifestyle counseling included diet, exercise, and weight loss and was calculated as the frequency of counseling per month. The time-weighted average HbA1c was also calculated. The composite primary outcome is the time to the first cardiovascular event (myocardial infarction, stroke, hospitalization for angina) or death by any cause. Secondary outcomes were time to death and time to the first cardiovascular event. For statistical analysis, the assessment of the association between lifestyle counseling frequency and patient outcomes was done by Cox proportional hazards models. There were adjustments made for patients’ demographics, comorbidities, non-lifestyle management (medications) of diabetes.
Patient pool included 19,293 patients who had a median baseline of 7.8% HbA1c. The median frequency of lifestyle counseling during hyperglycemic periods was 0.46 per month. Patients were followed for a mean of 5.4 years after the end of the treatment assessment period. Regarding univariable analysis, 16,057 patients received lifestyle counseling less than monthly; HbA1c decreased by 1.8% for patients who had monthly counseling or more vs 0.7% for patients who received less than monthly counseling (P<0.0001) after the 24 months treatment assessment period. Regarding the primary composite outcome, the 10-year cumulative incidence rate was 33% vs. 38.1% (P =0.0005). Using multivariable analysis to estimate primary composite outcome, once per month counseling vs. once per 3 months counseling had a hazard ratio of 0.88 (95% CI, 0.82,0.94; P<0,001). When time-weighted HbA1c was added, their relationship wasn’t statistically significant.
In conclusion, this study provided the association between lifestyle counseling and the risk of CVD events. Causation must be established by future studies. One of the limitations of the study is that they could not differentiate between patients with type 1 diabetes or patients with type 2 diabetes; they assumed that most of the patients had type 2 diabetes. Therefore, these results cannot be applied to patients with type 1 diabetes. Another consideration is that the medical centers were academic in nature. Therefore, it might not be generalizable to other medical centers.