Higher plasma pyridoxal 5′-phosphate is associated with better blood glucose responses in critically ill surgical patients with inadequate vitamin B-6 status

Background & aims: Stress, inflammation, and clinical conditions may increase the utilization and metabolic turnover of vitamin B-6 and lower the body pool of vitamin B-6. There is the possibility that hyperglycemia in critically ill patients might be at least partially due to compromised vitamin B-6 status. The purpose of this study was to compare blood glucose responses between critically ill surgical patients with adequate and deficient vitamin B-6 status. Methods: The study was designed as a cross-sectional observational study. Thirty-four patients in the surgical intensive care unit (SICU) were enrolled. The severity of illness (APACHE II score), the length of ventilation dependency, and the lengths of SICU and hospital stay were recorded. The levels of serum hemoglobin, hematocrit, albumin, prealbumin, C-reactive protein, glucose, insulin, glycated hemoglobin, C-peptide and creatinine were determined. Vitamin B-6 intake was recorded for 7 days. Vitamin B-6 status was assessed by direct measures [plasma and erythrocyte pyridoxal 5′-phosphate (PLP), pyridoxal (PL) and 4-pyridoxic acid (4-PA), and urinary 4-PA] and indirect measures [erythrocyte alanine and aspartate aminotransaminase activity coefficient]. Results: Fourteen patients were classified into the deficient vitamin B-6 group (plasma PLP < 20 nmol/L), while there were 20 patients in the adequate vitamin B-6 group. The mean serum glucose concentration of both groups indicated patients was in the hyperglycemic state (serum glucose > 126 mg/dL). However, mean serum glucose concentration significantly decreased by day 7 in the adequate vitamin B-6 group, whereas patients still remained in the hyperglycemic state (serum glucose > 126 mg/dL) in the deficient vitamin B-6 group. There were significantly correlations of relatively higher plasma PLP at admission (day 1) with the reduction of blood glucose concentration (r s = 0.72, p = 0.029) on day 7 in the deficient vitamin B-6 group. However, erythrocyte PLP concentration was positively associated with blood glucose level (r s = 0.88, p = 0.002) at admission in the deficient vitamin B-6 group after adjusting for age, gender, APACHE II score, diabetic history and insulin therapy. Conclusions: Surgically ill patients with adequate plasma PLP concentration at admission showed improved blood glucose response at day 7. Higher plasma PLP at admission was a major contributing factor in the reduction of glucose concentration in critically ill surgical patients with deficient vitamin B-6 status.