Background: Recent evidence correlates Alzheimer ‘s disease (AD) and diabetes mellitus (DM), through the involvement of reduced insulin-like growth factor (IGF-1). In acute myocardial infarction (AMI), low IGF-1 levels are correlated with a high risk of mortality and re-infarction. However, the DM-amyloid 1-40 (Aβ1-40) association in patients with coronary artery disease (CAD) remains unexplored.
Aim and Methods: To study Aβ1-40 concentrations based on glycaemic status, identify predictors of its levels, and assess the relationship between this peptide and IGF-1, we collected blood samples from 630 AMI patients on admission. Patients were classified into three groups based on haemoglobin A1c (HbA1c) levels: group 1 (189 patients without DM, HbA1c<39 mmol/mol), group 2 (270 patients with pre-DM, HbA1c 39-48 mmol/mol), and group 3 (171 patients with DM, HbA1c>48 mmol/mol).
Results: The cohort, mostly male (73.5%), had a mean age of 66.33 (11.28) years. Among them, 74.85% presented with ST-elevation myocardial infarction (STEMI), and 25.2% had a history of previous ischemic events. Median Aβ1-40 levels were 85.75 [53.85-128.67] pg/ml. Aβ1-40 positively correlated with age, tumor necrosis factor-alpha, HbA1c, HOMA-IR index, and TyG index. No significant correlation was observed between Aβ1-40 and IGF-1. Aβ1-40 levels increased from group 1 to group 3 (72.42 [48.79-109.26] pg/ml vs. 86.25 [53.4-125.54] pg/ml vs. 103.56 [61.78-46.31] pg/ml, respectively, 0.001). Although not statistically significant, DM patients tended to have lower IGF-1 values compared to those without DM, while pre-DM patients had the lowest values, suggesting poorer glycaemic control (groups 1, 2, and 3: 575.3 [326.75-864.75] pg/ml vs. 519.25 [294.08-800.48] pg/ml vs. 528.3 [216.2-836.6] pg/ml).
At logistic regression analysis, high levels of Aβ1-40 were predicted by older age, worse left ventricular systolic function, higher HOMA-IR index, higher levels of HbA1c, and poorer glomerular filtration rate (GFR), corrected by vitamin D. Conversely, lower levels of IGF-1 were predicted by older age, higher TyG index, higher HbA1c, low vitamin D levels, and compromised GFR.
Conclusions: Given the established link between Aβ1-40 and mortality in AMI patients, improved glycaemic control could reduce the levels of this peptide, counteract its pro-inflammatory properties and improve prognosis. Further investigations are needed to clarify the complex relationship between Aβ1-40 and IGF-1.