Abstract
Heart failure (HF) is a global epidemic, particularly affecting the elderly and/or frail patients often with comorbidities. Amongst the comorbidities, type 2 diabetes mellitus (T2DM) is highly prevalent and associated with higher morbidity and mortality. We review the detection and treatment of T2DM in HF and the need to balance the risk of hypoglycaemia and overall glycaemic control. Despite large attributable risks, T2DM is often underdiagnosed in HF. Therefore there is a need for systematic monitoring (screening) for undetected T2DM in HF patients. Given that patients with HF are at greater risk for developing T2DM compared with the general population, an emphasis also has to be placed on regular reassessment of glycaemic status during follow-up. Therefore, glucose-lowering therapies (e.g. sodium-glucose cotransporter-2 inhibitors, SGLT-2 inhibitors) with a known benefit for the prevention or delay of HF hospitalization could be considered early in the course of T2DM, to optimise treatment and reduce cardiovascular (CV) risk. Although intensive glycaemic control has been shown to effectively reduce the risk of microvascular complications in T2DM, these same trials have shown either no reduction in CV outcomes, or even an increase in mortality with tight glycaemic control (i.e. targeting HbA1c levels <7.0%). More lenient glycaemic targets (e.g. HbA1c levels 7.0-8.0%) may be more appropriate for HF patients with T2DM. The 2016 ESC Guidelines for the diagnosis and treatment of HF proposed metformin as the first-line therapy, given its long-standing use and low risk of hypoglycaemia. More recently, several novel glucose lowering-medications have been introduced, including dipeptidyl peptidase-4 (DPP-4) inhibitors, glucagon-like peptide-1 receptor agonists (GLP-1 RA), and SGLT-2 inhibitors. The most consistent reduction in the risk of HF hospitalisation has been shown with the three SGLT-2 inhibitors (empagliflozin, canagliflozin and dapagliflozin) which now offer improved outcomes in patients with both HF and T2DM.