Diabetes mellitus and heart failure are both highly prevalent conditions — and diabetes can itself be a cause of heart failure, which makes it worth understanding the specific pathophysiology and management implications when the two coexist. A 2019 scientific statement from the American Heart Association and Heart Failure Society of America addresses exactly this.¹
Why diabetes and heart failure go together
The prevalence of heart failure in patients with diabetes is four times higher than in the general population. Fasting hyperglycaemia, raised HbA1c, and insulin resistance are all independently associated with higher heart failure risk. These associations reflect specific metabolic and structural mechanisms: impaired glucose utilisation coerces the heart into preferential fatty acid oxidation, the ultimate consequence of which is diabetic cardiomyopathy.
The metabolic shift: from glucose to fat
Elevated free fatty acids are the hallmark of the cardiovascular pathophysiology of diabetes. They drive:
- Lipid accumulation within cardiomyocytes
- Increased mitochondrial reactive oxygen species
- Myocardial hypertrophy and increased left ventricular mass
- Higher rates of cardiomyocyte apoptosis
The mitochondria of heart cells are metabolically altered by this shift, which in turn affects the cell’s handling of calcium. Intracellular calcium is not only the critical mediator of myocardial contraction, but also a key regulator of mitochondrial — and, by extension, overall cellular — metabolism. The diabetic heart ends up both fat-laden and exposed to lipotoxicity, while the vasculature itself becomes more atherogenic.
Structural consequences: fibrosis and stiffness
The increase in ventricular mass also relates to increased fibrosis, driven by cross-linking of collagen molecules under the influence of advanced glycation end-products — themselves a product of chronic hyperglycaemia. The result is increased myocardial stiffness and impaired cardiac relaxation. A non-compliant, fatty heart resists fuller ventricular filling, and this diastolic dysfunction is an early functional manifestation of diabetic cardiomyopathy, present in 40–75% of patients with diabetes.¹
Hyperglycaemia also activates the renin-angiotensin-aldosterone system, adding its vasoconstrictive effects to the picture.
The diabetic heart at risk
Between the metabolic shift toward fatty acid oxidation and the structural changes driven by fibrosis and stiffness, the diabetic heart is placed at risk for both systolic and diastolic heart failure.
Reference
- Dunlay SM, Givertz MM, Aguilar D, et al. “Type 2 Diabetes Mellitus and Heart Failure: A Scientific Statement From the American Heart Association and Heart Failure Society of America” [published correction appears in J Card Fail. 2019 Oct;25(10):851]. J Card Fail. 2019;25(8):584-619. doi:10.1016/j.cardfail.2019.05.007
Leave a Reply