Afterward, it has been shown that in a cohort of 22 T2DM patients treated with conventional oral hypoglycemic therapy the assumption of capsules containing an ethanol extract of GS leaves (GS4) 400 mg/day for 18–20 months resulted in a reduction of FPG levels (−50.00 mg/dl, −40.30%, p < .001) and HbA1c values (−3.43%, −35.50%, p < .001) respect to baseline as well as an increase of insulin levels in the fasting (+8.00 mg/dl, +61.50%, p < .01) and post‐prandial state (+13.00 mg/dl, +26.00%, p < .01) compared to diabetics without supplement (Baskaran et al., 1990). This evidence concerns the gene INS and diabetes mellitus.