Since zinc is an element capable of influencing glucose homeostasis in animals and humans, a systematic review and meta-analysis of 14 randomized control trials (for a total of 3978 subjects, of which 3298 were healthy, 408 affected by T2DM, 48 with DM1, 48 with DM1 or T2DM, 120 with metabolic syndrome, and 56 obese subjects) evaluated the effect of zinc supplementation on fasting blood glucose, HbA1c, insulin, and blood zinc concentrations. Here, INS is linked to metabolic syndrome.