Impact of Uncontrolled Diabetes on Myocardial Global Longitudinal Strain: A Case–Control Study

Background: Subclinical systolic dysfunction due to diabetic microangiopathy and its impact on left ventricular (LV) function remains unclear. Myocardial deformation (strain) imaging can detect LV systolic dysfunction earlier than conventional ejection fraction evaluations. Thus, this study aimed to examine the relationship between uncontrolled diabetes and impaired LV global longitudinal strain (GLS) in patients with diabetes mellitus (DM) compared to non-diabetic individuals. Methods: A total of 76 asymptomatic patients with uncontrolled type 2 DM and 76 age- and gender-matched healthy controls underwent transthoracic echocardiography imaging. Patients with coronary artery disease, an LV ejection fraction <55%, atrial fibrillation, or inadequate echocardiographic quality were excluded. The presence of proliferative retinopathy, microalbuminuria, nephropathy, or peripheral neuropathy defines diabetic microvascular complications. Results: The absolute GLS% was significantly lower in the uncontrolled diabetic group (–18.4 ± 1.7) compared to controls (–22 ± 1.9, p < 0.001). Diabetic patients with complications had lower absolute GLS% values of –18.9 ± 1.7 for no complications, –17.5 ± 1.3 for one complication, and –16.8 ± 1.3 for two or more complications (p-value = 0.001). Regression analysis showed a positive association between complications and lower absolute GLS% (β = 0.41, p < 0.001). No significant difference was found in LV mass between hypertensive (155.1 ± 40.4) and non-hypertensive individuals (139.8 ± 44.3; p-value = 0.19). Conclusion: Uncontrolled diabetes and the presence of complications were associated with lower absolute GLS% values, suggesting impaired myocardial deformation. These findings highlight the importance of monitoring GLS% as a potential marker for cardiac involvement in diabetic patients.