Effects And Molecular Mechanism Of Combined Trivalent Chromium And Magnesium Supplementation On Glucose And Lipid Metabolism In Subjects With Insulin Resistance

Background:Studies have reported that chromium and magnesium deficiency have close association with the formation and development of insulin resistance, supplementing chromium or magnesium alone can alleviate insulin resistance and improve carbohydrate and lipid metabolism. However, the effects of a combination of chromium and magnesium supplementation in subjects with insulin resistance have not been reported until now. The molecular mechanism of the effects of chromium and magnesium supplementation on insulin resistance has not been studied adequately, which should be researched further.Objectives:To observe the effects of combined trivalent chromium and magnesium supplementation on the levels of blood glucose, insulin and blood lipid in subjects with insulin resistance; to explore the molecular mechanism of the effects of trivalent chromium and magnesium supplementation on insulin resistance by observing the changes in important signal molecules of insulin signal transmission pathway.Methods:A total of120subjects with insulin resistance aged45to59years were randomly divided into four groups:group A was provided placebo as control group:group B received trivalent chromium intervention as chromium group; group C was given magnesium intervention as magnesium group; group D was provided trivalent chromium and magnesium intervention as chromium and magnesium group. The intervention period was3months. Fasting blood samples before breakfast were collected before and after the intervention, serum was isolated to detect glucose and lipid metabolism indices and lymphocytes were isolated to extract RNA after being cultivated72h. Triglyceride(TG), total cholesterol(TC), high density lipoprotein cholesterol(HDL-C), low density lipoprotein cholesterol(LDL-C) and fasting blood glucose(FBG) were detected by an automatic analytical instrument; fasting insulin(FIns) was determined by radioimmunoassay; insulin resistance index (IRI) was calculated using homeostasis model assessment. The mRNA expressions of glucose transporter4(GLUT4) and glycogen synthase kinase3β(GSK3β) in lymphocytes were detected using quantitive real-time PCR.Results:1Glucose metabolism indices:FBG, FIns and IRI of group D decreased0.37mmol/L(P<0.01),2.91uIU/ml (P<0.01) and0.60(P<0.01) respectively after the intervention; although there were trends of reduction in FBG, FIns and IRI in group B and C, the differences were not statistically significant(P>0.05); results of comparisons among groups suggested there were significant differences in changes of FBG levels between group D and the other there groups(P<0.05) while there were no significant differences in other results of comparisons among groups(P>0.05).2Lipid metabolism indices:HDL-C increased0.16mmol/L(P<0.05) while TG, TC and LDL-C decreased0.29mmol/L(P<0.05),0.28mmol/L(P<0.05) and0.28mmol/L(P<0.05) respectively in group D after the intervention; HDL-C enhanced0.08mmol/L(P<0.01) and LDL-C reduced0.45mmol/L(P<0.05) in group B, although TG and TC had decreasing trends, there were no statistical differences(P>0.05); HDL-C of group C increased0.14mmol/L(P<0.01), there were trends of reduction in TG, TC and LDL-C in group C, but the differences were not statistically significant(P>0.05); results of comparisons among groups suggested there was significant difference in changes of HDL-C levels between group D and control group(P<0.01), there was significant difference in changes of HDL-C levels between group C and control group(P<0.05), while there were no significant differences in other results of comparisons among groups(P>0.05).3Results of quantitive real-time PCR:GLUT4mRNA of group D increased2.91(P<0.05) while GSK3β mRNA decreased0.45(P<0.05) after the intervention; although GLUT4mRNA had increasing trends and GSK3β mRNA had decreasing trends in group B and C, the differences were not statistically significant(P>0.05); results of comparisons among groups suggested there was significant difference in changes of GLUT4mRNA levels between group C and group D (P<0.05), while there were no significant differences in other results of comparisons among groups(P>0.05).Conclusions:Supplementing trivalent chromium combined with magnesium can increase HDL-C and decrease FBG FIns, IRI, TG, TC and LDL-C levels, which suggest supplementation of combined trivalent chromium and magnesium is beneficial to subjects with insulin resistance in improving glucose and lipid metabolism. The combination of trivalent chromium and magnesium supplementation can enhance the expression of GLUT4mRNA and reduce the expression of GSK3P mRNA, which suggest supplementation of combined trivalent chromium and magnesium may improve insulin resistance through affecting the expression of important signal molecules of insulin signal transmission pathway.This study was supported by national natural science fundation of china(81001296)...