Type 2 diabetes effects ~5% of Western populations, with prevalence rates significantly higher in East and South Asian communities. Non-alcoholic fatty liver disease (NAFLD) is reported to effect between 20 and 30% of Western populations, can be as high as 60% in urban East and South Asian groups, and is closely related to the development of Type 2 diabetes. Indeed, in excess of 90% of obese people with Type 2 diabetes have NAFLD. The strong relationship between NAFLD and Type 2 diabetes lies in the central role of the liver lipids in glucose homeostasis.
Heart disease is the leading cause of morbidity and mortality in both Type 2 diabetes and NAFLD. Individuals with diabetes demonstrate a 74% greater risk of hospitalisation due to heart failure. NAFLD, characterized by elevated serum γ-glutamyltransferase (GGT), is independently associated with heart failure. The increased incidence of cardiovascular morbidity and mortality associated with Type 2 diabetes and NAFLD, has been linked to preclinical changes in cardiac structure, function and metabolism.
The most commonly reported change in asymptomatic individuals with Type 2 diabetes is diastolic dysfunction, alongside decreased end-diastolic blood volume, and changes in cardiac strain patterns. These cardiac changes have been associated with myocardial steatosis, michondondrial dysfunction, changes in calcium regulation, and myocardial fibrosis. NAFLD is also characterized by a similar pattern of diastolic dysfunction, altered left ventricular geometry, reduced myocardial perfusion reserve and changes in cardiac strain. Although a growing body of epidemiological and clinical evidence links the disease processes of Type 2 diabetes and NAFLD, little is known about how these conditions may differentially affect the heart.
Using magnetic resonance imaging (MRI) we have previously shown pre-clinical changes in cardiac structure and function in NAFLD. To extent this work and in light of the importance of understanding early cardiac changes and reducing cardiovascular risk in people with metabolic disease, the present study was designed to compare the impact of Type 2 diabetes and NAFLD upon cardiac structure, function and metabolism and to identify potential metabolic mediators.