Relationship Between Blood Fatty Acids And Insulin Resistance In Patients With Impaired Glucose Tolerance And Type 2 Diabetes Mellitus

Objective: To investigate the change of plasma free fatty acids (FFA),fatty acid composition and the relationship between FFA,fatty acid composition and insulin resistance (IR) in patients with impaired glucose tolerance and type 2 diabetes mellitus.Methods: 1 .The subjects were divided into type 2 Diabetes (DM), impaired glucose tolerance (IGT), and normal glucose tolerance (NOT) according to fasting blood glucose and/or oral glucose tolerance test (OGTT). Serum FFA was measured by enzymatic colorimetric (ACS-ACOD). Serum lipids were measured by enzymatic assay. Serum glucose and insulin concentration were determined with glucose oxidase method and radioimmunoassay (RIA),respectively. Insulin resistance was evaluated with insulin action index (IAI). 2.Some patients were elected from three groups to measure plasma fatty acids composition by gas chromatography. Results: l.The level of serum FFA was higher in both IGT and DM than NGT(p<0.05),and it was higher in DM than IGT(pK0.05). IAI was lower in both IGT group and DM group than in NGT group(p<0.01).Serum TG concentrations werehigher in DM and IGT than NGT( p<0.01).Serum HDL-c concentration was lower in DM and IGT than NGT(p<0.01).2. There were negatively linear correlation between serum FFA ,body mass index (BMI) and IAI (r=--0.634, P0.001;r=-0.682, P<0.00 1, respectively) ; Serum FFA was positively correlated with 2h insulin after glucose load(r=0.475, P=0.005) ;Serum TG was significantly related to theIAI(r=-0.527, P=0.0072).3. There were positive correlation between FFA and BMI in IGT group (r=0.523 P<0.001) and DM group (r=0.519, P<0.001) .But no significantly difference was observed in NGT group (p>0.05).4.Plasma concentrations of palmitic acid (C16:0),stearic acid (C18:0),behenic acid (C22:0),lignoceric acid (C24:0) and total saturated fatty acid (SFA) were higher in DM and IGT than NGT group (all /K0.05).The concentrations of arachidonic acid(C20:4) increased from NGT to IGT and DM subgroup(p<0.05).No difference was observed in plasma linoleic acid(C18:2) levels,but it showed a downward tendency(p>0.05).No difference were observed in total monunsaturated fatty acid (MUFA),total polyunsaturated fatty acid (PUFA)(all p>0.05). PUFA/SFA was lowest in DM group and highest in NGT group(p<0.05).5.There were negatively linear correlation between plasma C16:0,C20:4,C22:0,SFA and IAI, and the correlation coefficients were -0.425,-0.394,-0.359 and -0.470,respectively(all P<0.01).PUFA/SFA was negatively correlated with IAI (r=0.568, P=0.005) .There were positively linear correlation between SFA and TG (r=0.376,P<0.05).PUFA/SFA were negatively correlated with TG and LDL-c ,and the correlation coefficients were -0.413 and -0.386 respectively (all PO.05). Conclusions: 1. In IGT and DM patients, serum FFA levels are higher, and IAI was lower. There are positive relation with IR,obesity and FFA. 2.Plasma fatty acid compositions are different in NGTJGT and DM group.Plasma SFA concentrations are higher in IGT and DM group than NGT group,and the ratio PUFA to SFA decreased in IGT and DM group . There are closed relation with SFA, PUFA/SFA and IR.The patients of DM and IGT can reasonably decrease SFA and increase PUFA in dietary to improve insulin sensitivity. 3.The patients of DM and IGT complicate with Obesity, hyperlipidemia, and the change of fatty acids compositions, which are risk factor of atherosclerosis. It is important reason to result in disease with great vessels. 4.Lipid metabolism disorder have existed in IGT.Lipotoxicity is important in the occurrenc and development of DM.