Fig. 2

Normalized distribution of fasting plasma glucose levels in the healthy group. The normalized distribution shows in green area, which was calculated by mirror symmetric transformation according to the area to the left of peak in the original plot (the blue wave line). In the normalized distribution, the pair of boundary values (3.0 mmol/L and 7.2 mmol/L) were observed at the 100% confidence interval, the other pair (3.9 mmol/L and 6.3 mmol/L) obtained at 99.7% confidence interval.