Objective: The effect of lifestyle intervention on clinical risk factors in patients with type 2 diabetes is unclear. The aim of this meta-analysis was to evaluate the effects of comprehensive lifestyle change, such as diet, exercise, and education, on clinical markers that are risk-factors for cardiovascular disease in patients with type 2 diabetes.
Methods: We searched Medline, Cochrane, EMBASE, Google Scholar (up to August 31, 2013) for randomized controlled trials that compared standard of care (control group) with treatment regimens that included changes in lifestyle (intervention group). The primary outcome was reduction in risk factors of cardiovascular disease including body mass index (BMI), glycated haemoglobin (HbA1c), systolic blood pressure (SBP), diastolic blood pressure (DBP), high-density lipoprotein cholesterol (HDL-c), and low-density lipoprotein cholesterol (LDL-c).
Results: A total of 16 studies were included in the meta-analysis. The standardized difference in means of change from baseline significantly favored the intervention compared with the control group in BMI (− 0.29; 95%CI, − 0.52 to − 0.06, P=0.014), HbA1c. (− 0.37; 95%CI, − 0.59 to − 0.14, P=0.001), SBP (− 0.16: 95%CI, − 0.29 to − 0.03, P=0.016), DBP (− 0.27, 95%CI=−0.41 to − 0.12, P<0.001). There was no difference between the intervention and control groups in HDL-c (0.05; 95%CI, − 0.10 to 0.21; P=0.503) and LDL-c (− 0.14; 95%CI, − 0.29 to 0.02; P=0.092).
Conclusions: The meta-analysis found that lifestyle intervention showed significant benefit in risk factors that are known to be associated with development of cardiovascular disease in patients with type 2 diabetes.
Alex’s Notes: This study out of China really caught my eye with “lifestyle intervention,” primarily because I am a huge advocate of fixing the causes rather than treating the symptoms, and there is no doubt that lifestyle factors are part of the problem in type-2 diabetics. This study specifically wanted to see what effect these interventions had on clinical markers of cardiovascular disease in type-2 diabetics. So the first question I had was what does lifestyle intervention mean?
Interventions included increased physical activity, reduced caloric intake, dietary education, and counseling and education regarding treatment adherence or disease monitoring. A total of 16 studies were included in the meta-analysis, with the number of patients per study ranging from 23 to 2575, the age ranging from 51-68 years, and the study duration ranging from six months to eight years. And of course, quality assessment revealed that all the studies were at a high risk of bias due primarily to not having blinded conditions.
BMI was significantly reduced by an average of 0.29, HbA1c was significantly reduced by 0.37, and systolic and diastolic blood pressure was significantly reduced by 0.16 and 0.27, respectively, in the lifestyle intervention groups compared to the controls. LDL and HDL cholesterol were not affected.
Now, I have to admit that these changes are quite unimpressive and their practical relevance is debatable. The inconsistencies of the included studies with regard to the type of lifestyle intervention may have played a role. For instance, only four of the included studies used exercise as an intervention, and another meta-analysis specifically assessed whether resistance exercise is comparable to aerobic exercise in regard to glycemic control, blood lipids, blood pressure, anthropometric measures, health status, and adverse events. They concluded that the difference between exercise regimens was not clinically important, and that physical activity in general may be more important than the choice of a specific exercise. Moreover, a review of nearly 100 studies assessed the role of physical activity on cardiovascular disease in subjects with diabetes and concluded that physical activity reduces the risk of cardiovascular disease in type-2 diabetics.
So with the above in mind, and considering that the majority of the interventions in the present meta-analysis were some form of counseling, a fairer conclusion would be that counseling has minor improvements for cardiovascular risk factors in type-2 diabetics. I wonder what they were counselled about.