Insulin Resistance And β-cell Function Of Islets Of Pancreas In Patients With Prior Coronary Heart Disease And Normal Fasting Blood Glucose

Coronary heart disease(CHD) is one of the principal diseases which harms papular health. Risk factors for CHD include hyperlipoidemia, hypertension, diabetes mellitus, smoking, hyperinsulinaemia, visceral obesity et al. Diabetes Mellitus is associated with coronary heart disease, and considered as the same dangerous disease with CHD.In recent years, it has been revealed by some clinical and prospective epidemiologic investigations about the relationship of hyperinsulinaemia,insulin resistance and CHD.The role of insulin resistance in the pathogenesis of atherosclerosis and CHD is hot.Insulin resistance(IR) is referred to decreased biological effect of insulin compared with the normal condition. The typical characters of IR are Glucose intolerance and hyperinsulinemia. Insulin resistance may leads to several abnormalities leading to CHD.These include (1) IR can make serious endothelium injury of arteries and proliferation of vascular smooth muscle cells;(2) IR can make hypertriglyceridaemia, reduced HDL cholesterol, elevated small dense LDL particles and these induce atherosclerosis and coronary artery diseases;(3) IR is associated with elevated PAI-1 activity, which may account for haemostasis disorders;(4) IR is increasingly being recognized as a chronic, low grade inflammatory state.Epidemiological studies confirm the relationship between IR and CHD, but not enough to show the causal relation of them,and in our country only a few investigatioins is on the insulin resistance state in the patients with CHD and normal fasting blood glucose (FBG) . This study is to explore the prevalence of abnormal glucose regulation,β-cell function of islets of pancreas and IR in patients with CHD and normal FBG.We studied 35 subjects with CHD and normal FBG and hospitalised in our hospital. Inclusion criteria were as follow: patients diagnosed as CHD according to the World Health Organization (WHO) criteria in 1979, part of them was verified by coronary angiography one or more than one coronary artery lumen reductions >= 50 %, or had the history of myocardial infarction; all of them were not diagnosed as diabetes mellitus before, and their FBG <6.1mmol/L.The study group consisted of 18 men and 17 women (mean age 52.8±10.3 years). Normal controls group consisted of 16 men and 14 women (mean age 52.1±8.2 years),and were healthy through medical examination.75-g oral glucose tolerance testing was performed on 35 patients with CHD and 30 patients as normal controls; plasma glucose and insulin after OGTT were measured at 0, 30, 60, 120and 180 minutes ;Insulin secretion and insulin resistance were evaluated and the following indexes were caculated:early insulin secretion index:△I30/△G30, HOMA-IR = FINS×FBG/ 22. 5,HOMA-βcell index:HBCI=20×FINS/ (FBG-3.5);Li's newβcell insulin secretion index: MBCI= ( FINS×FBG ) /(BG2h+BG1h-2FBG).Continuous variables were summarized as mean±SD.The intergroup comparisons were performed by a Student's t-test. Variables skewed pattern of distribution were natural logarithmically (ln)-transformed prior to any calculations in order to obtain the normal distribution.Categorical variables are presented as counts or proportions (%).Multivariate analysis was performed by logistic regression.Our study results show that In patients with CHD and normal FBG, 43%(15/35) had impaired glucose regulation or newly detected diabetes(2h BG≥7.8mmol/L), were higher than those of controls 23%(7/30)( P < 0.05) .Only use the FBG, the proportion of patients with abnormal glucose regulation was substantially lower than when the post-load plasma glucose (OGTT (2 h)) was considered , two fifths of patients with abnormal glucose regulation would have remained undiagnosed; insulin at 0, 120,180 minutes and HOMA-IR of patients with CHD were higher than those of controls(11.4±9.5 vs.5.32±3.2 mU/L,72.6±48.5 vs.32.2±22.0 mU/L,42.8±35.4 vs.8.7±6.9 mU/L ,0.63±0.32 vs.0.48±0.21,P<0.01),△I30/△G30,MBCI were lower than those of controls (1.12±0.65 vs.1.43±0.57,1.03±0.36 vs.1.36±0.38,P<0.01) ;Logistic regression analysis revealed that insulin at 120 minutes and HOMA-IR were positively correlated with the development of CHD (OR is 1.432,0.644, respectively,P < 0. 05); ROC curve analysis to define cut-off values of HOMA-IR and insulin at 0, 120minutes :HOMA-IR:0.54,insulin at 0 minutes:15.3 mU/L,insulin at 120 minutes:65.7 mU/L.From the total experiment we can conclude: (1) Abnormal glucose regulation in patients with CHD is higher than controls.An OGTT is a feasible tool to disclose the glucometabolic status of patients with CHD early; (2) An simplified OGTT is easy and convenient to disclose the glucometabolic status;(3) There are IR andβ-cell dysfunction of islets of pancreas in patients with CHD.