L-Arginine ameliorates insulin resistance in sickle cell anaemia in the steady state

Abstract

There is scanty information on the effect of L-arginine supplementation on glucose metabolism in HbSS patients. The effect of six weeks L-arginine supplementation (1g/day) on oral glucose tolerance test (OGTT) and insulin resistance (HOMA-IR was investigated in 40 adult HbSS and 40 adult HbAA subjects. After a 12-hour overnight fast, 3 mL of blood was withdrawn from an ante-cubital vein of each subject for the estimation of fasting blood glucose (FBG), insulin, L-arginine concentration [R], catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx) and MDA. OGTT was performed on each subject and then placed on L-arginine for 6 weeks. Parameters were re-measured at the end of the period. Before supplementation, FBG, fasting insulin, HOMA-IR, MDA were higher in HbSS subjects. CAT, SOD, GPX were higher in HbAA subjects. In response to OGTT, glucose and insulin peaked at 30 minutes in HbAA subjects and at 60 minutes in HbSS subjects. Supplementation did not affect these patterns of responses to OGTT. In HbSS subjects, L-arginine reduced FBG, insulin, HOMA-IR and MDA but increased insulin and HOMA-IR in HbAA subjects. Δ[R] correlated negatively with Δglucose, Δinsulin and ΔHOMA-IR respectively in HbSS subjects but positively in HbAA subjects. In HbSS subjects, ΔHOMA-IR correlated negatively with ΔCAT, ΔSOD and ΔGPx respectively but positively in HbAA subjects. Study thus showed impaired glucose and insulin responses to OGTT in HbSS subjects that were not affected by arginine. Supplementation ameliorated insulin resistance and oxidative stress burden in these subjects.