Cardiovascular autonomic neuropathy (CAN), a complication of T2D, affects the autonomic nerves innervating the heart and can adversely affect cardiac performance. Reduction in HRV is an early manifestation of CAN with parasympathetic loss preceding sympathetic dysfunction. Whether HRV is influenced by prior diabetes treatment or glycemic control in young adults with youth-onset T2D is not known.
Heart beats over 10 minutes from an ECG were measured by Sphygmocor to derive the normal R-R intervals (NN intervals). HRV outcomes included: the standard deviation of the NN intervals (SDNN), the root mean square differences of the NN intervals (RMSSD), and the frequency domain low to high (LF:HF) power. TODAY participants (n=400) 7 y post-randomization (T2D duration 7.7±1.5 y) were compared to 133 obese controls without T2D. We assessed whether prior randomized treatment (metformin alone, metformin+ rosiglitazone or metformin+ intensive lifestyle) or glycemic control over time (time-weighted HbA1c) were associated with HRV.
Compared to obese controls, TODAY subjects were younger (mean age 20.7±2.5 vs. 22.6±3.7 y) but not different by sex or BMI (35% male, BMI 36.6±8.1 kg/m2). TODAY participants had reduced overall HRV (SDNN; 57.9±29.6 vs. controls 67.1±25.4, p<0.0001), including a pattern of parasympathetic loss (RMSSD; 53.0±36.6 vs. controls 67.9±35.2, p<0.0001) with sympathetic overdrive (LF:HF power; 1.4±1.7 vs. controls 1.0±1.1, p<0.0001). Among TODAY subjects, HRV did not differ by previously randomized treatment, but higher HbA1c over time was independently associated with lower SDNN and RMSSD and higher LF:HF power independent of age, race, sex, T2D duration and BMI.
Young adults with youth-onset T2D show early manifestations of CAN with both parasympathetic and sympathetic impairments that are associated with higher HbA1c.
A.S. Shah: None. L. El Ghormli: None. F. Bacha: Research Support; Self; National Institute of Diabetes and Digestive and Kidney Diseases, Pediatric Diabetes Consortium. Other Relationship; Self; AstraZeneca, Jaeb Center for Health Research. R.M. Farrell: Stock/Shareholder; Self; Tandem Diabetes Care. S. Gidding: Research Support; Self; Color Genomics. L.E. Katz: None. J.B. Tryggestad: None. M. Vajravelu: None. N.H. White: None. E.M. Urbina: None.
National Institutes of Health; National Institute of Diabetes and Digestive and Kidney Diseases