Assessment of cardiac conduction defects in normotensive type 2 diabetic patients and their relation with diabetic nephropathy

Background: The prevalence of diabetes is increasing and is intimately associated with cardiovascular morbidity and mortality. The relationship between diabetes and conduction defects is complex and multifactorial, including autonomic dysfunction, atrial and ventricular remodelling and molecular alterations. Lower estimated glomerular filtration rate (eGFR) and albuminuria are associated with an increased risk of all-cause and cardiovascular mortality in patients with diabetes. This study aimed to determine the prevalence of conduction blocks, namely, atrioventricular (AV) nodal blocks, bundle branch blocks and fascicular blocks, in the electrocardiograms (ECGs) of normotensive patients with type 2 diabetes mellitus (T2DM) and to ascertain their relationship with eGFR and albuminuria. Aim: The objective of this study was to determine the relationship between eGFR and cardiac conduction defects in patients with type 2 diabetes and to assess albuminuria and its relationship with eGFR and HbA1C. Materials and Methods: This cross-sectional study included 240 cases of diabetes and 240 non-diabetic controls attending outpatient and indoor clinics in a tertiary care hospital. The clinical, biochemical and electrocardiographic characteristics of the patients were assessed. Spot urinary albumin–creatinine ratio (ACR) and eGFR were evaluated. Each ECG was thoroughly studied to determine the prevalence of certain cardiac conduction defects, such as bundle branch, fascicular and AV blocks. Results: The mean age was 55.95 ± 13.41 years in patients with T2DM and 53.17 ± 9.2 years in controls. The difference between mean HbA1C of 8.02 ± 1.92 in people with diabetes and 5.50 ± 0.27 in controls was significant ( P < 0.000). The mean spot ACR was 100.06 ± 172.41 in diabetics and 27.68 ± 23.99 in controls. The difference between the mean eGFR in diabetics and controls was significant ( P = 0.0159). The prevalence of cardiac conduction defects was higher (42.5%) in the T2DM group than in the control group (10%). With decreasing eGFR, there was a significant increase in the prevalence of cardiac conduction defects ( P = 0.0142). Conclusions: This study highlights a significantly higher prevalence of cardiac conduction defects in patients with T2DM, with right bundle branch block being the most common abnormality. Furthermore, conduction defects were more frequent in individuals with worsening renal function, as evidenced by a declining eGFR and increasing albuminuria. These findings suggest a strong interplay between diabetic nephropathy and cardiac conduction abnormalities.