Published in International Journal of Behavioral Medicine December 2015.
Diabetes, adiposity, and socioeconomic status (SES) are all associated with decreased heart rate variability (HRV), a marker of autonomic function predictive of mortality. Cambodians have high rates of diabetes and low SES. How these factors interact to explain HRV has not been examined.
The aims of this study were to investigate associations among waist-to-hip ratio, socioeconomic status, and HRV among Cambodians with diabetes.
Sixty patients with type 2 diabetes for ≥1 year, not taking insulin, aged 35-80 years were recruited from the Cambodian Diabetes Association. The 2010 Ministry of Health survey regarding household conditions was used to measure SES. Waist-to-hip ratio was measured two times and averaged. For HRV, beat-to-beat intervals were recorded on ambulatory ECG recorders, and short-term HRV was calculated in the time domain and in the frequency domain using spectral analysis. Cross-sectional data were analyzed using a series of multiple linear regressions using SPSS v21.
Participants were of mean age of 56 years old, 60 % female, with National Glycohemoglobin Standardization Program (NGSP) HbA1c mean = 8.4. Participants were poor (e.g., 18 % did not have flush toilets), had high waist-to-hip ratios (mean = 0.91), and had HRV values below published norms. In linear regression, there was a significant interaction between waist-to-hip ratio and SES explaining HRV in the time domain (standard deviation of the R-R interval (SDNN), beta = .33, t = 2.61, p < .05) and the frequency domain (log transformed very low frequency (Ln VLF), LF, and total power; all p < .05). Among those with lower SES only, higher waist-to-hip ratio was associated with lower HRV. Findings remained significant after controlling for age, sex, and HbA1c.
Central adiposity shows a stronger deleterious association with autonomic tone among individuals with more adverse social conditions.
Adiposity; Cambodians; Diabetes; Heart rate variability; Socioeconomic status; Waist-to-hip ratio