The Study Of Relationship Of Insulin Resistance And Islet Function With Blood Pressure In Patients With Isolated Impaired Fasting Glycaemia

Background and Purpose:Diabetes is one of the endocrine and metabolic diseases,associated with many complications.The stage of impaired fasting glucose(IFG)is known as prediabetes.Insulin resistance(IR)is the main pathophysiological mechanism of prediabetes,diabetes and its cardiovascular complications.In clinical practice,more than one third of patients with essential hypertension may have different degrees of IR.The prevalence of IFG in patients with hypertension is higher than that in people with normal blood pressure.Recently,the research on the relationship between IFG and blood pressure has become the focus of attention.Our previous experimental results confirmed that blood pressure control can improve the IR of IFG population.It is not clear for how long this benefit would last.Hence,long term study is needed.In order to further clarify the relationship between essential hypertension and IFG,we observed the long-term changes of IR in patients with hypertension in IFG population,and conducted a cross-sectional study to explore the correlation between different blood pressure levels and IR,which provided important scientific basis for delaying or preventing the occurrence and development of type 2diabetes mellitus.Methods:The experiment was divided into two parts.Part I: From October 2012 to September 2013,one hundred and eighty IFG patients were enrolled and divided into normal blood pressure group(n = 88)and essential hypertension group(n = 92)according their blood pressure.IFG Patients in the hypertension group received Levamlodipine Besylate pills or Losartan Potassium tablets(different types and dosages of drugs were selected according to the degree of essential hypertension patient’s condition).Blood pressure was lowered to less than 130/80 mm Hg.Patients,who were lost to follow-up,normalized blood-glucose levels,or developed into diabetes,were excluded from the study.At last,114 IFG patients completed 5 years of follow-up.The laboratory tests of the participants in 2015,2016 and 2017 were collected,including fasting plasma glucose(FPG),fasting insulin(FINS),postprandial 2 hours plasma glucose(2h PG),2 hours insulin(2h INS),the Homeostasis Model of insulin Resistance(HOMA-IR),insulin sensitivity index(ISI),blood lipid and uric acid(UA)levels were collected.Part II: In this cross-sectional study,180 IFG patients with essential hypertension were selected.They were divided into 3 groups according to hypertension grade.The first group(DH1 group)was IFG patients with the grade I hypertension(n=71),the second group(DH2 group)was IFG patients with the grade II hypertension(n=57),and the third group(DH3 group)was IFG patients with the grade III hypertension(n=52).FPG,2h INS,FINS,2h PG,Hb A1 c were collected.HOMA-IR and ISI were calculated.Results:Part I: The incidence of diabetes in the hypertension group(22.83%)was significantly higher than that in the normal blood pressure group(11.36%)(P<0.05);The index of FINS,2h INS,HOMA-IR and ISI in normal blood pressure group had no interaction with those in hypertension group(P=0.066,0.835,0.061 and 0.259,respectively).In all the IFG patients,FINS,2h INS and HOMA-IR increased significantly during the 3 years of follow-up(P<0.001),ISI decreased significantly(P<0.001).Compared with normal blood pressure group,the levels of FINS,2h INS and HOMA-IR in hypertension group were significantly increased(P<0.001),while ISI level in hypertension group was significantly decreased(P<0.001).We further analyzed the changes of HOMA-IR in normal blood pressure group and the hypertension group,respectively.In the normal blood pressure group,HOMA-IR level was significantly increased more in 2017 than that in 2015.While,in the hypertension group,there was a significant increase of HOMA-IR from 2015 to 2017 year by year.The index of Hb A1 c and HDL-C in normal blood pressure group had no interaction with those in hypertension group(P=0.429 and 0.995,respectively).There were no significant changes in Hb A1 c and HDL-C levels in the 3 years of follow-up(P=0.516 and0.989,respectively).Compared with normal blood pressure group,the levels of Hb A1 c and HDL-C in hypertension group were markedly higher(P=0.005 and 0.004,respectively).Part II: There were significant differences in the levels of FINS,2h INS,HOMA-IR and ISI among DH1,DH2 and DH3 groups.The levels of FINS,2h INS and HOMA-IR increased gradually from DH1 to DH3 group,and indexes mentioned above in DH3 group were significantly higher than those in DH1 group and DH2 group,respectively(P<0.05).The ISI level in DH3 group was significantly lower than that in DH1 group and DH2 group(P<0.05).Conclusion:Compared with IFG patients with normal blood pressure,patients with IFG and hypertension,despite antihypertensive treatment,still developed significant insulin resistance earlier and had higher Hb A1 c levels,and were more likely to progress to type 2diabetes.IR is closely related to the degree of blood pressure in IFG patients with hypertension.The higher the blood pressure is,the more serious the IR is,especially when the blood pressure is higher than 180/110 mm Hg.Therefore,although antihypertensive therapy can not reduce the IR level of IFG patients with hypertension to the level of IFG patients without hypertension,it is still possible to reduce the IR level of IFG patients with grade 3 hypertension to the level of IR of IFG patients with grade 1 or 2 hypertension.Of course,the changes of blood lipid and BMI levels,together with blood pressure,may affect IR in IFG patients with hypertension.