Psidium guajava is a plant found in many tropical and subtropical regions of the world. The present study was conducted to evaluate the role of Psidium guajava leaf powder fractions in type 2 diabetic rats induced by a high-calorie diet combined with dexamethasone. Powder fractions (≤ 125; 125–200μm) of Psidium guajava leaves were prepared using controlled differential pulverization and sieving, and unsieved powder was obtained by simple grinding. 300 mg/kg of one of the different fractions or the unsieved powder was administered daily, in conjunction with a high-calorie diet, followed by an intraperitoneal injection of dexamethasone for six weeks, to normoglycemic rats.

Six weeks after the induction of diabetes, and regarding antidiuretic activity, the powder fraction ≤ 125 μm maintained fasting blood glucose at the lowest level (91.00 ± 5.31 mg/dL) compared to rats in the diabetic group (138 ± 7.60 mg/ dL). Regarding the lipid profile, the total cholesterol level was significantly lower (P < 0.01) (50.1 ± 3.2 mg/dL) with the ≤ 125 μm fraction compared to that of rats in the diabetic group (116.3 ± 12.5 mg/dL). Regarding antioxidant activity, the malondialdehyde concentration with the ≤ 125 μm fraction was 6.35 ± 0.192 μM/g versus 14.95 ± 0.77 μM/g observed in rats in the diabetic group.

The leaves of Psidium guajava constitute a powerful antidiabetic agent that could be exploited as an alternative medicine against diabetes and its complications.