Teens with Type 2 Diabetes Show Signs of Damaged Heart Function

Teenagers with Type 2 diabetes may already show signs of impaired heart function, according to a new study that will be presented on June 12^th at The Endocrine Society's 93rd Annual Meeting in Boston.

"Past studies in adults with Type 2 diabetes show that their heart and blood vessels' ability to adapt to exercise may be impaired. Our study shows that these changes in heart function may begin to happen very early after Type 2 diabetes occurs," said Teresa Pinto, MD, the study’s lead author and a pediatric endocrinologist at the Dalhousie University IWK Health Centre in Halifax, Nova Scotia, Canada.

The study was performed at the University of Auckland in New Zealand.

Pinto and researchers formed three groups of subjects: group one was comprised of thirteen teenagers who had type 2 diabetes; group two was made up of twenty-seven overweight, non-diabetic subjects; and group three contained nineteen non-obese, non-diabetic control subjects. The ages of the fifty-nine total participants ranged from twelve to twenty.

The researchers studied how the heart and blood vessels of the teens in each group adapted to exercise. Their body composition, including percentage of body fat, was determined using dual-energy x-ray absorptiometry (DEXA) scans.

Each participant underwent an exercise test on a stationary bicycle designed for use in a magnetic resonance imaging (MRI) machine. Using the MRI, images were taken of each participant’s heart and femoral artery, the blood vessel in the leg that supplies the limb with blood. The MRI imaging occurred while the participants were at rest, as well as during or immediately following work out on the bike.

The images taken showed that the hearts of teens with Type 2 diabetes did not expand and fill up with blood between heartbeats as well as the hearts of subjects in the other two groups. The authors discovered that this occurred during exercise only, however.

With exercise, the amount of blood pumped out with each heartbeat was normal in all three groups, although still notably decreased in the diabetic group.

"We showed that the heart's pumping function is strong, but it is not filling as well as normal between heart beats. This is known as diastolic dysfunction," Pinto said. "Although this study did not determine the reason for this, we know that with diabetes, the heart can become stiffer, limiting its ability to stretch and expand."

Further, images taken of the femoral artery showed that the blood flow through the artery was considerably decreased in the diabetic participants during exercise in comparison to the other two groups.

"It appears that irrespective of weight, Type 2 diabetes seems to have a negative effect on the heart and blood vessels in adolescents," Pinto said. "This impaired exercise capacity may be reversible with exercise training however, as some literature in adults suggests, but further studies are required to determine this."