Global Longitudinal Strain in Type 1 and Type 2 Diabetes: Why Similar Abnormalities May Not Mean the Same Thing

Global longitudinal strain (GLS) is increasingly used to detect subclinical myocardial dysfunction in diabetes, but similar abnormalities may not carry the same biological meaning in type 1 diabetes (T1D) and type 2 diabetes (T2D). In T1D, chronic hyperglycemia, oxidative stress, microvascular dysfunction, and progressive interstitial remodeling may contribute prominently to impaired myocardial deformation. In T2D, insulin resistance, adiposity, lipotoxicity, mitochondrial dysfunction, and altered myocardial energetics may have greater influence, although substantial mechanistic overlap exists. This review examines how these differing pathophysiological contexts influence the interpretation of GLS, the evolution of myocardial dysfunction, and reported responses to contemporary cardiometabolic therapies. Complementary deformation parameters are also considered where they provide additional insight into ventricular mechanics. Importantly, GLS is a sensitive marker of myocardial dysfunction but is not mechanism-specific and may be influenced by metabolic, hemodynamic, and loading conditions. Interpretation should therefore incorporate diabetes subtype, disease duration, glycemic burden, comorbidity, and complementary imaging findings. A mechanistically informed approach may improve the clinical and research interpretation of myocardial deformation in diabetes.