INS and type 2 diabetes mellitus: This American study demonstrated lowering of most of the evaluated HRV parameters (particularly the SDNN, standard deviation of the 5-minute average NN intervals [SDANN], TP, ultra-low frequency [ULF], and very low frequency [VLF] power) in patients with markedly elevated FG (6.1–6.9 mmol/L) and type 2 diabetes (with FG > 6.9 mmol/L or on antidiabetic medication or insulin) in comparison with the patients with normal (4.5–5.5 mmol/L) and slightly elevated (5.6–6.0 mmol/L) FG.