October 16, 2006

Diet and Exercise Fight Metabolic Syndrome

October 16, 2006 (AIDSmeds)—A new study suggests that improvements in diet and exercise can help manage some of the signs and symptoms of the "metabolic syndrome" in people with HIV. Taking healthy steps to manage the metabolic syndrome, Kathleen Fitch, MD, of Massachusetts General Hospital and her colleagues suggest in their report in the September 11th issue of AIDS, may reduce the risk of cardiovascular disease and diabetes.

The metabolic syndrome, documented in approximately 25% of Americans, is a constellation of health problems that includes obesity, insulin resistance, increased cholesterol and triglycerides, and elevated blood pressure. This syndrome has been established and defined by the National Cholesterol Education Program (NCEP). Left uncontrolled, the metabolic syndrome greatly increases the risk of heart disease and diabetes.

Between 17% and 45% of HIV-positive people, many of whom are taking HIV drugs known to cause metabolic problems, are also believed to have the metabolic syndrome. While there are federal guidelines supporting the use of lifestyle modifications – dietary changes and improved exercise habits – that have been shown to decrease the risk of diabetes and cardiovascular disease in HIV-negative people, there haven't been any concrete data indicating a similar effect in HIV-positive people with the metabolic syndrome.

The study conducted by Dr. Fitch's team was the first-ever clinical trial to evaluate the benefits of a lifestyle modification program in HIV-positive people who meet the NCEP criteria for the metabolic syndrome. The lifestyle modification program included in the study was based on the National Institute of Digestive and Kidney Diseases (NIDDK) Diabetes Prevention Program (DDP).

Thirty-four HIV-positive patients receiving HIV treatment and presenting with at least three signs or symptoms of the metabolic syndrome were enrolled. Half of the patients received intensive one-on-one DDP counseling; the remaining patients were followed in a no-intervention control group. All patients were asked to provide physical activity questionnaires, seven-day food diaries, and submit to an exercise stress test at the beginning and end of the study.

After six months, a number of statistically significant differences between the two groups were documented.

There was a 2.6 cm average decrease in waist circumference – an indicator of obesity – among those in the intervention group (down from 113.7 cm at study entry), compared to a 1.2 cm increase in the control group (up from 101.1 cm at study entry).

Systolic blood pressure – the first, or top, number of the blood pressure reading – decreased by an average of 13 points in the intervention group (down from 138), compared to an increase of four points in the control group (up from 131).

Improvements in hemoglobin A1C – used to find out if a patient's blood sugar is under control over time – were also significant, with an average decrease from 5.4% to 5.3% in the intervention group, compared to an average increase from 5.4% to 5.6% in the control group.

Physical activity improvements were also seen in those who received DDP counseling. Such activity was measured using energy expenditure scores called "METs," with rigorous or prolonged activities receiving the highest scores. Total physical activity was measured in MET-hours/week – the MET intensity of each activity multiplied by the hours per week of that activity, then adding all activities together.

Dr. Fitch's group reported that MET scores improved by 17.7 hours a week in the intervention group after six months, compared to a MET score decrease of 33.1 hours/week in the control group. The differences in MET scores between the two groups after six months were statistically significant.

While there wasn't a statistically significant difference between the two groups with respect to exercise stress testing, the slight improvements seen in the intervention group, compared to the slight decreases in the control group, were highlighted by the study authors.

Some of the more traditional markers of diabetes or cardiovascular risk, such as glucose levels, cholesterol, and triglycerides, did not differ between the two groups after six months. This is a discouraging finding, in light of the fact that these traditional markers usually do improve in HIV-negative people with the metabolic syndrome who undertake lifestyle modifications. Dr. Fitch's team suggests that such modifications may be of limited benefit in people remaining on HIV drugs known to cause glucose and lipid problems.

Despite the shortcomings noted in the study, Dr. Fitch and her colleagues suggested that DDP lifestyle modifications were associated with a number of statistically significant improvements in various metabolic syndrome parameters that may reduce the risk of diabetic and cardiovascular risk in people with HIV.

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