Impact of Duration of Disease and Glycosylated Haemoglobin Level in Determining the Severity of Coronary Artery Disease in Patients with Type-2 Diabetes Mellitus: A Prospective, Cross-sectional, Observational Study

Abstract

Introduction: Duration of Type 2 Diabetes Mellitus (T2DM) and degree of glycaemic control play a pivotal role in the development of macrovascular complications of T2DM, including Coronary Artery Disease (CAD). However, association of the duration of T2DM and Glycosylated Haemoglobin (HbA1c) level with the severity of CAD is still an ongoing matter of debate in the diabetic patient subset. Aim: To investigate the association of duration of T2DM and HbA1c level with severity of CAD in patients presenting with T2DM suspected of CAD. Materials and Methods: This prospective, cross-sectional, observational study was conducted on 500 T2DM patients at GNRC Medical, Guwahati, Assam, India from June 2017 to June 2019. The T2DM patients with suspected CAD were studied and stratified according to the duration of T2DM (<10 and >10 years) and HbA1c level (<7% or ≥7%). All patients underwent coronary angiography to assess number of diseased vessels i.e., insignificant CAD (defined as <50% diameter stenosis in left main and <70% diameter stenosis in other branches), Single Vessel Disease (SVD), Double Vessel Disease (DVD), Triple Vessel Disease (TVD), and Left Main Coronary Artery (LMCA) disease. Chi square test was used to assess the correlation of the duration of T2DM and HbA1c level with angiographic severity of CAD. The data were analysed using the Statistical Package for Social Sciences (SPSS) version 16.0, (Chicago, IL, USA). Results: A total of 500 patients were studied, of which, 295 (59%) and 205 (41%) patients had <10 and ≥10 year duration of T2DM, respectively. Overall, 264 (52.8%) patients had HbA1c <7%, and 236 (47.2%) had ≥7%. Normal coronary artery (42.4% vs. 5.9%; p=0.00001), insignificant CAD (9.8% vs. 2.4%; p=0.00124), SVD (21% vs. 6.8%; p=0.00001), and LMCA disease (2.4% vs. 13.2%; p=0.00001) were significantly higher in patients with <10 year duration of T2DM than ≥10 year. On the other hand, DVD (12.9% vs. 28.8%; p=0.00001), and TVD (11.5% vs. 42.9%; p=0.00001) were significantly higher in patients with ≥10 year duration of T2DM as compared to <10 year. Normal coronary artery (34.8% vs. 19.1%; p=0.0001), and insignificant CAD (10.2% vs. 2.9%; p=0.0013) was higher in patients with HbA1c level <7% than ≥7%. The prevalence of TVD (18.6% vs. 30.9%; p=0.0013), and LMCA disease (3.8% vs. 10.2%; p=0.0047) were significantly lower in patients with HbA1c level <7 than ≥7%. Conclusion: The T2DM patients with suspected CAD, longer duration of T2DM and poor glycaemic control were associated with more severe CAD.