PCSK9 and diabetes mellitus: This recent study with small numbers explored four groups of patients and the mean PCSK9 level in each of these cohorts [group 1 (diabetes and no DR): 0.24 ± 0.09 ng/mL, group 2 (diabetes and non-proliferative DR): 0.29 ± 0.08 ng/mL, group 3 (diabetes and proliferative DR): 0.38 ± 0.11 ng/mL, group 4 (matched controls with no diabetes): 0.13 ± 0.07 ng/mL].