Letter to Yang T, Fu P, Chen J, et al. Increased risk of adverse cardiovascular events by strict glycemic control after percutaneous coronary intervention in type 2 diabetes mellitus combined with acute coronary syndrome. Curr Med Res Opin. 2021;37(9):1517–1528

Yang et al.¹ conducted a prospective study to evaluate the association between HbA1c level and long-term clinical outcomes in type 2 diabetes mellitus (T2DM) patients in combined with acute coronary syndrome (ACS), who had undergone percutaneous coronary intervention (PCI). The 5-year incidence rate of major adverse cardiovascular events (MACEs) in HbA1c <6.0% and 6.0–6.5% groups were similar to 7.5–8.0% and ≥8.0% groups, which were significantly higher than in 6.5–7.0% and 7.0–7.5% groups. By multivariate analysis, there was a U-shaped relationship between 2-year HbA1c level and risk of MACEs. Regarding their recommendation of prohibiting strict glycemic control after PCI in T2DM patients, I present an additional information with special reference to mortality risk.

Choi et al.² conducted a prospective study to evaluate the risk of all-cause mortality in T2DM patients with ACS, who had undergone PCI. The patients with a mean HbA1c of 6.5–7.0% had the lowest all-cause mortality, and the adjusted hazard ratio (95% CI) of patients with a mean HbA1c ≤ 6.5% and those with a mean HbA1c > 8.0% against those with a mean HbA1c of 6.5–7.0% for all-cause mortality were 2.00 (1.02–3.95) and 3.35 (1.78–6.29), respectively. They mentioned that there was a J-curve relationship between mean HbA1c values and all-cause mortality, and patients under 65 years of age presented no significant relationship. Taken together, the less strict glycemic control in T2DM patients with ACS and PCI would be optimal for lowering all-cause mortality, especially in elderly patients. Although the increased risk of the strict glycemic control for MACEs and all-cause mortality cannot be explained logically, the poor nutritional condition may partly relate to subsequent health risk. The mechanism of linking low mean HbA1c to MACEs and all-cause mortality should be clarified in T2DM patients with ACS and PCI.

Transparency

Declaration of funding

This paper was not funded

Declaration of financial/other relationships

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Acknowledgement

None.