NEFL and diabetic neuropathy: When separately analyzed to detect subgroup differences based on type of peripheral neuropathy (Figure 2, Figure 3, and Figure 4), diabetic neuropathy had increased NFL (SMD, 0.77 [95% CI, 0.42 to 1.13]; P < .001; I2 = 0%) and S100B (SMD, 0.93 [95% CI, 0.60 to 1.25]; P < .001; I2 = 99%).