Patients who are prediabetic have similar microvascular dysfunction as diabetics, but exercise can help improve it, researchers reported here.

A 6-week aerobic exercise program helped improve brachial artery flow-mediated dilatation from 5.7 to 11.2 (P<0.0001), according to a pilot study by Sabyasachi Sen, MD, from Baystate Medical Center in Springfield, Mass., and colleagues.

The intervention also improved the fasting lipid profile of patients and reduced inflammatory markers, such as high-sensitivity C-reactive protein, Sen reported at the annual meeting of the American Association of Clinical Endocrinologists (AACE).

The healthier the blood vessel, the better the vascular reactivity as measured by brachial artery flow-mediated dilatation. It is known that those with diabetes have poor vascular reactivity compared with non-diabetics, but the literature is sparse regarding the endothelial function of those with prediabetes, Sen said.

“We wanted to first measure the vascular reactivity and then see if exercise can actually make a difference to the blood vessel, because diabetes management should not only be about glucose control,” Sen told MedPage Today.

The baseline flow-mediated dilatation for these prediabetic patients was 5.6, which is comparable to those with diabetes (P=0.0027), Sen said.

“If you would have asked me before the study what to expect, I wouldn’t have predicted their vessel reactivity would be almost as poor as those with diabetes,” Sen said.

“The good thing is that exercise improves vessel function almost back to normal status, which is not the case with diabetes. It’s been shown that exercise only improves the vascular reactivity of diabetics by half of what we achieved here,” he said.

Sen and his colleagues said the implications are that there is a therapeutic window for prediabetics to return their vascular function to normal with a non-pharmacologic intervention like aerobic exercise and in turn “reduce the cardiovascular risk in a patient population that is at risk of developing diabetes.”

For the pilot study, they recruited 20 people with prediabetes. Participants served as their own controls in this crossover study. For 6 weeks, half the group participated in the exercise program and half did not. Then there was a 4-week washout period, followed by another 6 weeks where participants crossed over to exercise or no exercise.

The exercise consisted of 150 minutes per week at 70% of the maximum heart rate, which is considered moderate exercise by American Diabetes Association criteria, Sen said.

At baseline, patients had a mean age of 52, body mass index (BMI) of 30.3, percentage of fat of 35.1, fat mass of 68.3, and blood pressure of 125/76 mm Hg.

“These were not hypertensive patients,” Sen said. “They were fairly active but not undergoing any type of formal exercise program.”

Researchers found that the exercise program did not significantly affect weight, fat mass, or blood pressure, but significantly improved vessel reactivity.

In addition, they saw significant changes in biomarkers, such as a decrease in high-sensitivity C-reactive protein, leptin, and interleukin-6. Although HDL cholesterol did not significantly increase, apolipoprotein A1, a negative component of HDL, significantly decreased.

“The traditional classification of prediabetes is based on glucose levels, but maybe we should also measure vascular reactivity. After all, it’s the vascular dysfunction that contributes toward stroke, heart disease, and death,” Sen said in an interview.

The study was limited because 90% of the patients were Caucasian and the sample size was small, Sen said. He added that he plans to do a larger study to determine if longer follow-up with the same exercise regimen leads to weight loss and continues the positive trends seen in the biomarkers.

Primary source: American Association of Clinical Endocrinologists
Source reference: Sen S, et al “Vascular Reactivity improves in Pre-diabetes Patients, post aerobic exercise” AACE 2012; Abstract 305.

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