Increase in fasting blood sugar tied to higher risk of silent heart attack: Study

The study, published in Cardiovascular Diabetology, higher longitudinal fasting glucose and larger intra-individual variability in FG over time were associated with a higher silent myocardial infarction (SMI) risk in a dose-response manner.

Silent myocardial infarction, characterized by the absence of typical symptoms such as chest pain, presents a formidable challenge in early detection and intervention. Often lurking beneath the surface, this stealthy assailant can exact a heavy toll on cardiovascular health, precipitating adverse outcomes and mortality. Against this backdrop, understanding the nuanced interplay between blood glucose dynamics and silent MI assumes paramount significance.

In the intricate tapestry of cardiovascular health, the role of blood glucose levels has emerged as a critical determinant, particularly concerning silent myocardial infarction. A groundbreaking pooled analysis of four cohort studies was conducted by Amy C. Alman, College of Public Health, University of South Florida, Tampa, FL, USA, and colleagues to investigate the longitudinal association between FG and silent MI and also delve into the nuanced aspect of dose-response.

For this purpose, the researchers analyzed data from 24,732 individuals from four prospective cohort studies, who were free of MI history at baseline. Average FG and intra-individual FG variability (coefficient of variation) were calculated, and SMI cases were identified using 12-lead ECG exams with the Minnesota codes and medical history. The average mean age of the study population was 60.5 years with a median fasting glucose of 97.3 mg/dL at baseline.

During the study's follow-up period, FG was measured for each subject. A Cox regression model with time-dependent variables was applied to assess the association between FG and SMI after adjustment for gender, age, race, smoking, study, low-density lipoprotein level, longitudinal BMI, serum creatinine, and blood pressure.

Based on the study, the following inferences were made:

• During an average of 9 years of follow-up, 357 SMI events were observed (incidence rate, 1.3 per 1000 person-years).
• The association between FG and SMI was linear, and each 25 mg/dL increment in FG was associated with a 15% increase in the risk of SMI. This association remained significant after adjusting for using lipid-lowering medication, antidiabetic medication, antihypertensive medication, and insulin treatment (HR 1.08).
• Higher average FG (HR per 25 mg/dL increase: 1.17) and variability of FG (HR per 1 sd increase: 1.23) over visits were also correlated with increased SMI risk.

In conclusion, increased longitudinal FG, average FG, and intra-individual variability of FG over time were all associated with an increased risk of silent MI during follow-up in this study population after adjusting for multiple confounders including medication use.

"Given the asymptomatic or atypical nature of SMI, these results emphasize routine cardiac screening, particularly for patients with elevated glucose, as a crucial approach for preventing silent myocardial infarction and promoting heart health," the researchers concluded.

Reference:

Xiao, M., Malmi, M.A., Schocken, D.D. et al. Longitudinal blood glucose level and increased silent myocardial infarction: a pooled analysis of four cohort studies. Cardiovasc Diabetol 23, 130 (2024). https://doi.org/10.1186/s12933-024-02212-3