| Summary: | <p>Abstract</p> <p>Background</p> <p>Non-enzymatic glycation increases hemoglobin-oxygen affinity and reduces oxygen delivery to tissues by altering the structure and function of hemoglobin.</p> <p>Objectives</p> <p>We investigated whether an elevated blood concentration of glycosylated hemoglobin (HbA1c) could induce falsely high pulse oximeter oxygen saturation (SpO<sub>2</sub>) in type 2 diabetic patients during mechanical ventilation or oxygen therapy.</p> <p>Methods</p> <p>Arterial oxygen saturation (SaO<sub>2</sub>) and partial pressure of oxygen (PO<sub>2</sub>) were determined with simultaneous monitoring of SpO<sub>2</sub> in 261 type 2 diabetic patients during ventilation or oxygen inhalation.</p> <p>Results</p> <p>Blood concentration of HbA1c was >7% in 114 patients and ≤ 7% in 147 patients. Both SaO<sub>2</sub> (96.2 ± 2.9%, 95% confidence interval [CI] 95.7-96.7% vs. 95.1 ± 2.8%, 95% CI 94.7-95.6%) and SpO<sub>2</sub> (98.0 ± 2.6%, 95% CI 97.6-98.5% vs. 95.3 ± 2.8%, 95% CI 94.9-95.8%) were significantly higher in patients with HbA1c >7% than in those with HbA1c ≤ 7% (Data are mean ± SD, all p < 0.01), but PO<sub>2</sub> did not significantly differ between the two groups. Bland-Altman analysis demonstrated a significant bias between SpO<sub>2</sub> and SaO<sub>2</sub> (1.83 ±0.55%, 95% CI 1.73% -1.94%) and limits of agreement (0.76% and 2.92%) in patients with HbA1c >7%. The differences between SpO<sub>2</sub> and SaO<sub>2</sub> correlated closely with blood HbA1c levels (Pearson’s r = 0.307, p < 0.01).</p> <p>Conclusions</p> <p>Elevated blood HbA1c levels lead to an overestimation of SaO<sub>2</sub> by SpO<sub>2</sub>, suggesting that arterial blood gas analysis may be needed for type 2 diabetic patients with poor glycemic control during the treatment of hypoxemia.</p>
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