HbA1c and prolonged hospital stay
There are differences between studies in their definition of a prolonged hospital stay (from ≥3 to 14 days) 51–53, which sheds interesting light on the association between HbA1c and length of hospital stay (LOS).
In a retrospective study (n=570), extended LOS was defined as > 3 days12. They found that HbA1c was an independent predictor of hospital stay regardless of blood sugar levels (p  = 0.001). Moreover, Medhi et al. found similar LOS results in 135 patients who underwent coronary artery bypass surgery; HbA1c ≥7% was found to be strong predictor of LOS ≥ 6 days (p  = 0.025)52. However, interestingly, when defining prolonged LOS as ≥ 14 days, LOS was not affected by preoperative HbA1c levels (with a cut-off of HbA1c = 7% for optimal and suboptimal levels;p = 0.367) 53.
It is noted that diabetic patient’s undergoing CABG, HbA1c levels significantly correlated with postoperative length of stay (LOS). Patients with suboptimal medium-term glycaemic control (HbA1c > 7%, n=38) had longer LOS than patients with optimal medium-term glycaemic control (HbA1c ≤ 7%, n=57) (mean postoperative LOS 6 days vs. 7.5 days; postoperative LOS mean rank: 32 days vs 46 days; p = 0.008) 47.
The meta-analysis of five studies (n = 3,002) conducted by Wang et al. reported a higher preoperative HbA1c level resulted in a 1.08-day mean increase in hospital stay after cardiac surgery (WMD = 1.08, 95% CI 0.46-1.71) 48.
On the other hand, intensive care stay was not affected by the level of HbA1c as several studies reported no significant difference in ICU days between patients with lower preoperative HbA1c levels and those with higher HbA1c levels after cardiac surgery 45,46,54,55.