Table 5.

The regression coefficients (β) estimates and standard error (SE) of Log-HOMA-IR on HRV indices using 24-hour data, daytime (9 AM to 9 PM) and nighttime (9 PM to 9 AM next day) data separately from linear mixed-effects models analysis.

			HRV index
			Log of HF (ms2)		Log of LF (ms2)		SDNN (ms)		RMSSD (ms)		LF/HF Ratio		Heart Rate (bpm)
			Beta	SE	Beta	SE	Beta	SE	Beta	SE	Beta	SE	Beta	SE
Log HOMA-IR	M 1	24-h	-0.23	0.028**	-0.24	0.021**	-3.58	0.31**	-1.93	0.34**	0.086	0.062	2.85	0.41**
		day	-0.26	0.034**	-0.22	0.027**	-3.44	0.38**	-1.86	0.35**	0.35	0.083**	2.80	0.60**
		night	-0.19	0.043**	-0.26	0.030**	-3.73	0.49**	-1.87	0.58**	-0.18	0.092*	2.88	0.52**
	M 2	24-h	-0.32	0.028**	-0.29	0.021**	-4.85	0.33**	-2.64	0.37**	0.27	0.066**	3.34	0.46**
		day	-0.33	0.035**	-0.28	0.029**	-4.31	0.39**	-2.32	0.37**	0.52	0.086**	3.21	0.68*
		night	-0.30	0.040**	-0.31	0.032**	-5.40	0.52**	-2.78	0.62**	0.011	0.10	3.36	0.58**

Abbreviations: BPM, beats per minute; HF, high frequency power; HOMA-IR, homeostasis model assessment of insulin resistance; HRV, heart rate variability; LF, low frequency power; Log, logarithm; M, mean; RMSSD, square root of the mean of the sum of the squares of differences between adjacent RR intervals; SDNN, standard deviation of all RR intervals.

Models: M1, unadjusted; M2, adjusted for age, sex, race, hypertension, and cardiovascular diseases.

Beta = one SD increase of Log HOMA-IR.

*, and **, P < 0.05, and P < 0.001, respectively.