Worst glycaemic status is associated with higher circulating amyloid beta 1-40 in patients with acute myocardial infarction

Background Little is known about the relationship between Aβ1-40 and type 2 diabetes mellitus (DM), in patients with coronary artery disease (CAD), although the same relationship in Alzheimer's disease (AD) is well-established. In addition, low levels of insulin-like growth factor (IGF-1) have been found to contribute to type 2 DM in AD and its low levels have been associated with an increased risk of mortality and re-infarction in patients with acute myocardial infarction (AMI). Purpose To investigate the Aβ1-40 concentration based on the glycaemic status, features that could predict its levels in patients with AMI and to access the relationship between Aβ1-40 and IGF-1. Methods Blood samples were collected from 630 patients with AMI at admission. Patients were stratified into three groups according to haemoglobin A1c (HbA1c) levels: group 1 including 189 patients without DM (HbA1c<39 mmol/mol), group 2 comprising of 270 patients with pre-DM (HbA1c 39-48 mmol/mol) and group 3 with 171 patients having DM (HbA1c>48 mmol/mol). Results The total cohort was predominantly male (73.5%) with a mean age of 66.33 (11.28) years. 74.85% of patients presented with STEMI, and 25.2% had a previous history of ischemic events. The median concentration of Aβ1-40 was 85.75 [53.85 – 128.67] pg/ml. Aβ1-40 positively correlated with age, tumour necrosis factor alpha, HbA1c, HOMA-IR index, and TyG index. No significant correlation was observed between Aβ1-40 and IGF-1. Comparing the groups, Aβ1-40 levels increase significantly 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 – 146.31] pg/ml, respectively, p<0.001), (Fig. 1a). Although not significant, patients with DM had lower IGF-1 values compared to those without, while pre-DM patients had the lowest values of this marker (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), (Fig. 1b). We hypothesize that the lower values of IGF-1 in the second group are due to poor glycemic control. On logistic regression analysis, high levels of Aβ1-40 were predicted by older age (OR: 1.02, p=0.02), worse LVEF(OR: 1.03, p<0.01), higher HOMA-IR index (OR: 1.02, p=0.05), higher levels of HbA1c (OR: 1.02, p<0.01) and worse GFR (OR: 1.02, p<0.01), corrected by vitamin D. While lower levels of IGF-1 were predicted by older age (OR: 1.03, p<0.01), higher TyG index (OR: 1.52, p=0.02) and HbA1c (OR: 1.02, p=0.01), low vitamin D levels (OR: 1.02, p=0.04) and worse GFR(OR: 1.01, p=0.04). Conclusions Given the association between Aβ1-40 and mortality in patients with AMI established in the literature, the strength and novelty of our research is that better glycaemic control could lower the levels of this biomarker and its pro-inflammatory properties, thereby improving the prognosis of patients. Further studies are required to clarify the relationship between Aβ1-40 and IGF-1.