Table 2.

Summary of characteristic features of included studies

Characteristic features of included studies	Number	%
Total patients	650	100
Patients with diabetic retinopathy	128	20
Patients with diabetic nephropathy	90	14
Patients with metabolic syndrome	95	15
Patients with prediabetes	78	12
Patients with type 2 diabetes	259	40
Coenzyme Q10 supplementation	323	50
Placebo	327	50