Effects Of Different Doses Of Metformin On Renal Function After Coronary Angiography In Patients With Type 2 Diabetes Mellitus

Background:In patients who undergo percutaneous coronary angiography(CAG),patients with type 2 diabetes mellitus(T2DM)are at increased risk of developing diseases such as contrast-induced nephropathy(CIN).When kidney function is impaired,metformin can accumulate in large quantities in the body,causing hyperlactic acidemia or lactic acidosis(LA).Whether metformin in patients with type 2 diabetes mellitus has an effect on renal function during CAG remains controversial.This study aimed to evaluate the safety of metformin in patients with type 2 diabetes receiving CAG.Method:Through retrospective analysis and randomized controlled grouping,T2DM patients with CAG admitted to the Department of Cardiology of Subei People’s Hospital of Jiangsu Province from September 2020 to December 2022 were collected as research subjects.According to the Expert Consensus on the Clinical Application of Metformin(2018 Edition)[1],metformin is within the recommended dose range(500～2000 mg·d-1),and the hypoglycemic effect is positively correlated with the dose and is dose-dependent.The principle of dose adjustment of metformin is "start with a small dose and increase it gradually".At the beginning of taking 500～1000mg/d,1～2 weeks after the dose can be increased to the best effective dose of 2000mg/d or the maximum tolerated dose.Therefore,we grouped according to the different doses of metformin,divided into 56 cases in the control group,41 cases in the low-dose group and 52 cases in the high-dose group,the control group did not use metformin,the use of metformin in the low-dose group was<1000mg/d,the metformin in the high-dose group was>1000mg/d,and the patients taking metformin used a single component of metformin ordinary tablets(500 mg/tablet).Renal function indexes[uric acid(UA),blood urea nitrogen(BUN),creatinine(Cr),estimated glomerular filtration rate(eGFR)]and lactic acid(Lac)levels were observed and compared between the three groups of patients before and after CAG surgery,Multivariate logistic regression analysis was used to evaluate the risk factors for CIN and LA.Outcome:There was no significant comparison of clinical data and serum detection indexes in the three groups of the control group,the low-dose group and the high-dose group(P>0.05).A total of 11 patients(7.4%)had CIN in 149 patients,including 4(7.1%)in the control group,3(7.3%)in the low-dose group and 4(7.7%)in the high-dose group,and the difference between the three groups was not statistically significant(P=0.994).No cases of lactic acidosis were found in the three groups,and there were no significant changes in relative lactate value and absolute lactate value before and after surgery(P>0.05).Multivariate logistic regression analysis was performed on the relevant factors of CIN,among which age,history of smoking and alcoholism,preoperative eGFR,etc.were risk factors for CIN,and hemoglobin,systolic blood pressure and left heart ejection fractio were protective factors.Conclusion:The dose of metformin did not increase the incidence of CIN and the risk of LA after CAG in patients with type 2 diabetes mellitus,but advanced age,low eGFR,and cardiac insufficiency increased the risk of CIN incidence.