Cigarette Smoking Is Associated with Prolongation of the QTc Interval Duration in Patients with Type 2 Diabetes Mellitus

Table 2

Mean values (±SD) of frequency-domain parameters of HRV during 24-hour, day, and night periods.

Variable	Chronic smokers	Nonsmokers	𝑃
Total power 24 hours (ms^2)	2339 ± 1864	2242 ± 1212	0.800
Total power day (ms^2)	1984 ± 1570	1768 ± 894	0.497
Total power night (ms^2)	2734 ± 2733	2800 ± 1877	0.908
Low frequency (LF) power 24 hours (ms^2)	585 ± 684	561 ± 436	0.862
LF power 24 hours in normalised units (nu)	64.36 ± 11.79	65.87 ± 11.02	0.590
LF power day (ms^2)	482 ± 531	428 ± 307	0.616
LF power day (nu)	63.46 ± 9.45	65.74 ± 11.57	0.389
LF power night (ms^2)	768 ± 1186	754 ± 762	0.955
LF power night (nu)	66 ± 14.01	66.76 ± 11.40	0.809
High frequency (HF) power 24 hours (ms^2)	208 ± 374	181 ± 200	0.707
HF power 24 hours (nu)	19.39 ± 7.79	19.28 ± 8.37	0.956
HF power day (ms^2)	170 ± 295	114 ± 140	0.331
HF power day (nu)	17.89 ± 7.74	16.27 ± 6.78	0.374
HF power night (ms^2)	284 ± 576	257 ± 309	0.815
HF power night (nu)	21.26 ± 10.17	21.1 ± 9.17	0.946
LF/HF ratio 24 hours	4.15 ± 2.64	4.24 ± 2.31	0.771
LF/HF ratio day	4.6 ± 3.03	5.01 ± 2.78	0.566
LF/HF ratio night	4.55 ± 3.95	3.91 ± 2.17	0.423

Day period: 09:00–21:00; night period: 23:00–06:00.