Effect of the ethanolic leaf extract of Moringa oleifera on insulin resistance in streptozotocin induced diabetic rats

Insulin resistance plays a central role in the pathogenesis of type 2 diabetes mellitus. Ameliorating insulin resistance helps to improve glycaemic control and hence reduce the risk of development and progression of diabetic complications. The extract of Moringa oleifera has been shown to improve hyperglycaemia, however, little is known on its effect on insulin resistance and beta-cell function. The objective of this study was to determine the effect of the ethanolic leaf extract of Moringa oleifera on insulin resistance in high-fat diet and streptozotocin induced diabetic rats. Different doses (250 and 500 mg/kg) of the ethanolic leaf extract of Moringa oleifera were administered orally for two weeks, to high-fat diet and streptozotocin induced diabetic rats, and were compared with metformin 320 mg/kg and control group (distilled water 10 ml/kg) for the effect on fasting blood glucose, serum insulin and insulin resistance (HOMA). The extract of Moringa oleifera (at doses of 250 mg/kg and 500 mg/kg) significantly lowered the fasting blood glucose at days 7 and 14 compared to controls (p = 0.0021 and p = 0.0001 respectively). There was a significant increase in serum insulin level in the control group at days 7 and 14 compared to the groups treated with the extract (250 mg/kg, 500 mg/kg) and metformin (p<0.01, p<0.02 and p<0.01 respectively). The extract at both doses and metformin (320 mg/kg) induced a significant improvement in insulin resistance (HOMA-IR) on days 7 and 14 (p < 0.0001).