The study, of 123 middle-aged and older adults, found that those who added yoga classes to standard diabetes care shed a handful of pounds over three months. Meanwhile, their average blood sugar levels held steady -- in contrast to the non-yoga-practicing "control" group, whose blood sugar levels rose.
The findings do not suggest that yoga should replace other forms of exercise for people with type 2 diabetes which is commonly associated with obesity.
Shreelaxmi V. Hegde of the Srinivas Institute of Medical Science and Research Center in Mangalore, India stated that, to really lose weight and rein in blood sugar, more-vigorous exercise would work better.
Among the 60 study participants who took yoga classes several times a week, the average BMI -- declined from 25.9 to 25.4. A BMI between 25 and 30 is considered overweight.
Hegde, the lead researcher on the work mentioned that, "In our study the effect of yoga on BMI (body mass index) and blood sugar control was marginal." "But," she added, "it should be noted that yoga controlled the blood sugar levels which otherwise rose in the control group." In addition to that, the study found, signs of so-called oxidative stress declined in the yoga group.
Oxidative stress refers to a situation where levels of reactive oxygen species or "free radicals" -- damaging byproducts of energy use in cells -- rise beyond the body's capacity to neutralize them. Long-term oxidative stress is believed to contribute to a host of chronic diseases.
In this study, Hegde's team measured participants' blood levels of certain chemicals that reflect oxidative stress. They found that, on average, the yoga group's levels of the chemicals dipped by 20 percent.
The significance of that is not clear. Hegde said that if such a decline in oxidative stress were sustained over time, it might lower the chances of diabetes complications, which include heart and kidney disease, nerve damage and damage to the blood vessels of the eyes.
Further, long-term studies are needed to see whether that is the case, the researchers say.
According to Hegde, yoga may curb oxidative stress because it stimulates the parasympathetic nervous system -- the part of the nervous system that basically acts as a brake against the gas pedal of the sympathetic nervous system.
There are caveats. The yoga used in this study was a gentle form, Hegde said, and parts of the practice were adapted for people who had additional health problems; certain poses were avoided in people who had heart disease, for example.
In the real world, yoga classes vary widely. Some are vigorous work-outs involving complicated poses that would not be appropriate for older adults with chronic health conditions.
Older adults with diabetes can look for yoga classes designed specifically for older people and those with chronic medical conditions. In the U.S., hospitals and local community centers are increasingly offering such classes.
Diabetes Care, online August 11, 2011