Poor Glycemic Control Is Associated With Increased Extracellular Volume Fraction in Diabetes

We assessed whether poor glycemic control is associated with an increase in myocardial fibrosis among adults with diabetes.

We studied 47 adults with type 2 diabetes and stratified them into three groups according to their hemoglobin A1c (HbA_1c) level: <6.5% (group 1; n = 12), 6.5-7.5% (group 2; n = 20), and >7.5% (group 3; n = 15). Left ventricular (LV) mass was assessed using cardiac MRI. The extracellular volume fraction (ECVF), an index of myocardial fibrosis, was measured by using myocardial T1 mapping before and after the administration of a gadolinium-based contrast agent.

Mean HbA_1c was 5.84 ± 0.16%, 6.89 ± 0.14%, and 8.57 ± 0.2% in groups 1, 2, and 3, respectively. LV mass was not significantly different between the groups. The myocardial ECVF was significantly greater in groups 2 (mean 27.6% [95% CI 24.8-30.3]) and 3 (27.6% [24.4-30.8]) than in group 1 (21.1% [17.5-24.7]; P = 0.015). After adjusting for age, sex, BMI, blood pressure, and estimated glomerular filtration rate, the myocardial ECVF was significantly greater in groups 2 (27.4% [24.4-30.4]) and 3 (28% [24.5-31.5]) than in group 1 (20.9% [17.1-24.6]; P = 0.0156, ANCOVA).

An increased myocardial ECVF, suggesting myocardial fibrosis, is independently associated with poor glycemic control among adults with diabetes. Further research should assess whether tight glycemic control can revert fibrosis to healthy myocardium or ameliorate it and its adverse clinical consequences.