HbA1c of ∼7.5% (58 mmol/mol) was associated with the lowest all-cause mortality rate (13).
However, the fact that A1C ever rising >7% (53 mmol/mol) was associated with CVD hospitalization may have important clinical ramifications for newly diagnosed patients.
An HbA1c level >7.5% (58 mmol/mol) was associated with a significantly increased all-cause mortality rate (hazard ratio [HR] 1.74 [95% CI 1.2 1.8], P < 0.0001).
Among patients without history of CVD, HbA1c above 7% (53 mmol/mol) was associated with 22% increased risk for CVE (HR CI: 1.14, 1.29; p < 0.01).
Within this group of patients, HBA1c >8.5%6969 nmol/mol) was associated with an even higher mortality rate, although this difference did not reach statistical significance.
Ever crossing above the threshold of 7% (53 mmol/mol) was associated with a 39% increased probability of CVD (1.39 [1.08–1.79]; P = 0.010).
A reduction in HbA1c by 1% (11 mmol/mol) was associated with a 14% decrease in fatal and nonfatal myocardial infarction (MI) (P < 0.0001), as well as 12% decrease in fatal and nonfatal stroke (P = 0.035).
An increase in HbA1c of 1% (11 mmol/mol) was associated with relative risk for cardiovascular disease of 1.21 (95% CI 1.13 1.29 for males and 1.11 1.31 for females; P < 0.001).
After 15-year follow-up, an increase in HbA1c of 1% (11 mmol/mol) was associated with hazard ratio (HR) of 1.19 (1.11–1.27) for coronary heart disease and 1.34 (1.22–1.48) for stroke (2).
Interestingly, in our systematic review (2) the lowest baseline A1C level (<8% [64 mmol/mol]) was associated with the highest success rate in achieving A1C <7% (55%, 95% CI 22.9 84.8), but this was not significant (P = 0.10), probably due to the small numbers of trials (only three trials with a mean baseline A1C <8%).
Furthermore, the regression analysis showed that a higher first insulin dose per kilogram of body weight by 0.1 IU or a lower HbA1c value at admission by 10 mmol/mol was associated with a lower mean BG by 5 mg/dL and 4 mg/dL, respectively.
