Differential effects of oral versus intravenous hydrocortisone and dexamethasone on capillary blood glucose levels in adult inpatients - a single centre study.

Background: Corticosteroids raise blood glucose concentrations; however, it remains unknown which form of administration, oral or intravenous, is associated with the greatest degree of blood glucose rise in hospitalised patients. Furthermore, it is not known whether the pattern of the associated hyperglycaemia throughout the day differs depending on the route of administration.

Methods: This was a single centre retrospective study of 384 adult inpatients receiving oral or intravenous hydrocortisone and dexamethasone. Data on capillary glucose concentrations and time taken over 7 days were collected. A mixed model for repeated measures was applied to compare changes in glucose concentration over time for oral and intravenous corticosteroids. An auto-regressive covariance structure was employed to model correlations between repeated measurements. This was adjusted for age, sex, pre-admission diabetes, and/or pre-admission corticosteroid status.

Results: No significant difference was found between oral and intravenous hydrocortisone on day 1 or across all 7 days (mean difference 0.17 mmol/L (-1.39, 1.75), p = 0.827, and mean difference 0.20 mmol/L (-0.61, 1.01), p = 0.639 respectively). There were no differences in mean glucose concentrations between those on oral or intravenous dexamethasone on day 1 or across all 7 days (mean difference 0.41 mmol/L (-0.55, 1.38), p = 0.404 and mean difference -0.09 mmol/L (-1.05,0.87), p = 0.855, respectively).

Conclusion: This study found that oral and intravenous administration of hydrocortisone and dexamethasone do not have a significantly differing impact on blood glucose levels. Capillary glucose monitoring is strongly recommended in all individuals who are on either oral or intravenous corticosteroids.