Among adolescents with type 1 diabetes, greater central adiposity and BMI standard deviation score were predictors of poor heart rate variability, independent of glycemic control and insulin dose for body weight, according to findings from a longitudinal study.
“Cardiac autonomic neuropathy has been linked to an increased risk of mortality in adults with diabetes, mediated through increased cardiovascular risk factors and associations with complications,” Kim C. Donaghue, PhD, FRACP, of the Children’s Hospital at Westmead and the Institute of Endocrinology and Diabetes in Westmead, Australia, and colleagues wrote in the study background. “However, there are limited data on the impact of BMI on cardiac autonomic function in adolescents with type 1 diabetes.”
Donaghue and colleagues analyzed data from 253 children and adults aged 8 to 30 years with type 1 diabetes, recruited between February 2009 and January 2012 (49% boys and men; mean age, 14 years; mean diabetes duration, 7.1 years; mean HbA1c, 8.3%). Researchers assessed heart rate variability measures, including standard deviation of R-R intervals (SDNN), time between consecutive QRS complexes, root mean squared difference of successive R-R intervals (RMSSD), triangular index, and low to high frequency ratio. Researchers used generalized estimating equations to model longitudinal associations between heart rate variability measures and clinical variables, including BMI SD score, waist-to-height ratio, total daily insulin dose and HbA1c.
At baseline, 22% of participants had overweight and 11% had obesity. Mean follow-up duration was 4.5 years (mean age at final visit, 19 years; mean final HbA1c, 9%; 29% with overweight and 12% with obesity). At follow-up researchers observed that the presence of any cardiac autonomic abnormality was higher vs. baseline, retinopathy increased from 12% to 28%, and the number of participants with an elevated albumin excretion rate increased from 21% to 29%.
Using generalized estimating equations, researchers found that BMI SD score was a predictor of lower heart rate variability, as measured by SDNN and RMSSD, with results persisting after adjusting for HbA1c. An overweight or obese BMI and higher waist-to-hip ratio also predicted lower heart rate variability measured by lower SDNN and RMSSD in alternative models, according to researchers.
Additionally, higher HbA1c and total daily insulin dose predicted lower heart rate variability and higher sympathetic tone (P < .05 for all).
“Prevention and early identification of young people with overweight and obesity, in addition to optimizing glycemic control and physiological insulin delivery, may improve long-term cardiac profile in type 1 diabetes,” the researchers wrote. – by Regina Schaffer
Disclosures: The authors report no relevant financial disclosures.