Background: 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.
Purpose: The aims of this study were to investigate associations among waist-to-hip ratio, socioeconomic status, and HRV among Cambodians with diabetes.
Method: 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.
Results: 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.
Conclusion: Central adiposity shows a stronger deleterious association with autonomic tone among individuals with more adverse social conditions.
Keywords: Adiposity; Cambodians; Diabetes; Heart rate variability; Socioeconomic status; Waist-to-hip ratio.