IJCS | Volume 33, Nº4, July and August 2020

364 Figure 1 - Cardiac autonomic dysfunction in adolescents with and without a family history of type 2 diabetes mellitus. SDNN: standard deviation of all NN intervals; RMSSD: root mean square of successive differences of NN intervals (ms); LF: low frequency; HF: high frequency. One-tailed, unpaired Student's t-test. Control vs. family history of diabetes (p < 0,05); es: effect size. HF (ms 2 ) LF (ms 2 ) Controls FHD Controls FHD Controls FHD Controls FHD p = 0.01 es = 0.39 p = 0.04 es = 0.31 p = 0.02 es = 0.37 p = 0.008 es = 0.28 Table 2 - Variability analysis of heart rate in adolescents without a family history of diabetes (controls) and adolescents with a family history of diabetes (FHD) Controls (n = 46) FHD (n = 23) p Effect size Time domain Total variance (ms 2 ) 1649.31 ± 1154.67 1532.4 ± 1154.60 0.6614 0.10 Mean RR (ms) 823.7 ± 19.85 767.2 ± 20.69 0.0724 2.80 pNN50 (%) 32.67 ± 3.083 24.00 ± 3.327 0.0784 2.73 Non-linear SD1 (ms) 37.14 ± 2.334 29.73 ± 2.348 0.0439 3.16 SD2 (ms) 66.66 ± 3.545 54.14 ± 2.623 0.0186 3.82 Frequency domain LF (nu) 45.17 ± 2.465 43.27 ± 2.681 0.6250 0.74 HF (nu) 54.83 ± 2.465 56.73 ± 2.681 0.6250 0.74 LF/HF 1.039 ± 0.1156 0.8844 ± 0.1111 0.3867 1.35 pNN50: percentage of adjacent NN intervals differing by more than 50 milliseconds; SD1: standard deviation of the variation in the beat-to-beat interval; SD2: standard deviation of continuous or long-term variability of RR intervals; nu: normalized units; ms: milliseconds; ms²: milliseconds squared; LF: low-frequency component; HF: high-frequency component; data presented as mean ± standard error; Student’s t-test. Controls vs FHD (p < 0.05). The size effect was calculated according to the Hedges’g method. Dias-Filho et al. Family history of diabetes and autonomic nervous system Int J Cardiovasc Sci. 2020; 33(4):360-367 Original Article