Effects of the consumption some dietary tropical vegetable oils on glucose metabolism in high fat induced- diabetic rats: a case-control study

Some vegetable oils, which are rich in antioxidants, and other phytochemical properties have been found to be useful for glycaemic control in animal studies. The effects of some tropical vegetable oils on glycemic control and some associated mechanisms in diabetic rats were therefore, assessed. Twenty (20) high-fat-induced type 2 diabetes male Spraque-Dawley rats selected from 30 high-fat diet fed rats were randomly divided into four groups of five each. The first group was fed on chow (control), whereas the remaining three groups were each fed on chow supplemented by 10% vegetable oil by weight of different oil: coconut oil, groundnut oil or palm oil added to rodent chow. After 42 days of feeding, 3.0 ml fasting blood sample was taken from each rat. Plasma glucose, was enzymatically determined. Insulin, IL-6 and anionic phospholipid levels and the expression of Glut 2 and 4 were assessed by ELISA method. Data was analysed using ANOVA, Tukey’s test and Pearson correlation analysis. Fasting blood glucose (FBG) was significantly reduced by 35% (p < 0.05), and 40% (p < 0.05), in the coconut and groundnut oil fed rats, respectively, however, palm oil non significantly reduced FBG levels by 17.4%. Rats fed on the groundnut oil diet presented significantly (p < 0.05) increased insulin, PI3K and GLUT 4 and non-significant change in the GLUT 2 levels. There was a reduced insulin resistance (p < 0.05), despite significantly increased levels of IL-6 (p < 0.05). There was a nonsignificant negative correlation between IL-6 and insulin resistance in each experimental group. The results reveal that groundnut and coconut oils significantly reduced fasting blood glucose levels (p < 0.05), whereas palm oil tended to reduce fasting blood glucose levels. In addition, groundnut oil showed a significantly (p < 0.05) improved insulin levels and increased sensitivity. However, the groundnut oil group also presented elevated levels of IL-6, indicating potential complexity in the interactions among vegetable oils in blood glucose regulation, insulin, and inflammation.