April 2, 2014

DynaMed Resident Focus is an outlet for residents to share recent evidence they find important with their peers. Residents who are members of the DynaMed community are eligible to participate. If interested, please email dynamedcommunity@ebscohost.com.

Weight Loss and Improved Fitness Slow Decline in Mobility in Overweight Adults with Type II Diabetes

Reference: N Engl J Med. 2012 Mar 29;366(13):1209-17, (level 1 [likely reliable] evidence)

Type 2 diabetes mellitus is a disease whose prevalence continues to increase, largely because it arises most commonly in overweight individuals. As our population has come to have increased access to food and the need for physical activity is nearly absent, we have unintentionally paved the path for the ever-growing presence of diabetes. As of 2011, according to the Center for Disease Control and Prevention (CDC), diabetes affected 25.8 million people in the U.S. (8.3% of the population) (CDC.gov). Loss of mobility is a potential consequence of having type 2 diabetes. The risk of decline in mobility is even higher in those who are overweight or obese. This all leads to ill-fated consequences such as muscle deterioration, the end of independence, and hence, an unacceptable decline in quality of life. In addition, this leads to institutionalization and greater health care costs; the CDC estimated direct and indirect healthcare costs of $174 billion (USD) in 2010 CDC.gov). All of this begs the question: can lifestyle intervention improve mobility and reduce the likelihood of disability among adults with obesity and type 2 diabetes?

A single blinded randomized controlled trial enrolled 5,145 overweight or obese adults between the ages of 45-74 years with type 2 diabetes. From 2001 to 2004 the recruits were randomized to receive an intensive lifestyle intervention or diabetes support and education. The lifestyle modification involved weight loss via portion control and promotion of physical activity, with the two primary goals being a mean weight loss of greater than 7% and an increase in the duration of physical activity to more than 175 minutes per week. The participants in the intervention group met for weekly group meetings in the first 6 months followed by biweekly meetings for the next 6 months. For the remainder of the study there was a minimum of one in-person visit per month and one other contact by phone, electronic or traditional mail. The diabetes education (control) group consisted of three group sessions per year with discussions centering on nutrition, physical activity and support. Self-reported limitations in mobility were the primary outcome (using 6 of 11 items on the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) Physical Functioning subscale), with assessments occurring annually for 4 years. Severe disability was defined as having severe limitations in nearly all tasks.

There were no significant differences between study groups in baseline clinical characteristics. At the end of year 4, the lifestyle intervention group had a 6.2% weight loss versus 0.9% in the diabetic support group (P<0.001). Also, significantly more patients in the experimental group had good mobility (38.5% vs 31.9%; NNT=16) and less participants had severe disability (20.6% vs 26.2%; NNT =18). The treatment group in comparison to the control group had a significant reduction of risk in mobility-related disability (odds ratio, 0.52, 95% CI 0.44 to 0.63). Weight loss and improved fitness (gauged by treadmill testing) both contributed independently to this reduction (P<0.001 for both variables). Follow-up was complete for 99% of study participants; data from at least 1 follow-up visit was required for inclusion.

It is encouraging that both a reduction in weight and an improvement in fitness level reduced the decline in mobility in overweight adults with type 2 diabetes. Often this type of intervention is difficult to reproduce in the clinical setting. However, these results give our patients hope for a greater quality of life and our health care system a chance for reduction in future costs.

For more information, see Physical activity for type 2 diabetes in DynaMed.

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