Impaired Glucose Metabolism in Patients with Heart Failure

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Abstract
The firm association of diabetes mellitus with congestive heart failure (CHF) has been undoubtedly established. Recent reports support the presence of the reciprocal interrelationships between CHF and glucose abnormalities. The present review provides an overview of some aspects of the multifactorial interrelationships between heart failure and diabetes mellitus. Patients with heart failure are generally at higher risk of developing type 2 diabetes mellitus. Several factors may be involved, such as a lack of physical activity, hypermetabolic state, intracellular metabolic defects, poor muscle perfusion, and poor nutrition. Serum levels of inflammatory cytokines and leptin are elevated in patients with heart failure. Activation of the sympathetic system in CHF not only increases insulin resistance but also decreases the release of insulin from the pancreatic β cells, increases hepatic glucose production by stimulating both gluconeogenesis and glycogenolysis, and increases glucagon production and lipolysis. People who develop type 2 diabetes mellitus usually pass through the phases of nuclear peroxisome proliferator-activated receptor modulation, insulin resistance, hyperinsulinemia, pancreatic β-cell stress and damage leading to progressively decreasing insulin secretion, and impaired fasting and postprandial blood glucose levels. Once hyperglycemia ensues, the risk of metabolic and cardiovascular complications also increases. It is possible that the cornerstone of diabetes mellitus prevention in patients with CHF could be controlled by increased physical activity in a cardiac rehabilitation framework. Pharmacologic interventions by some medications (metformin, orlistat, ramipril and acarbose) can also effectively delay progression to type 2 diabetes mellitus in general high risk populations, but the magnitude of the benefit in patients with CHF is unknown. In patients with CHF and overt diabetes mellitus, ACE inhibitors may provide a special advantage and should be the first-line agent. Recent reports have suggested that angiotensin receptor antagonists (angiotensin receptor blockers), similar to ACE inhibitors, provide beneficial effects in patients with diabetes mellitus and should be the second-line agent if ACE inhibitors are contraindicated. Treatment with HMG-CoA reductase inhibitors should probably now be considered routinely for all diabetic patients with CHF, irrespective of their initial serum cholesterol levels, unless there is a contraindication.