Mixed insulin can improve control of prednisolone-induced hyperglycaemia

Hyperglycaemia is a common side effect of prednisolone, although there are no widely accepted guidelines for the management of glucocorticoid-induced hyperglycaemia (GIH). Our institution uses mixed insulin in a pre-breakfast or pre-breakfast and pre-lunch regimen, with the rationale that this profile of insulin action matches the physiological effect of prednisolone on blood glucose levels (BGLs).

Evaluate the use of the mixed insulin (NovoMix30) in a pre-breakfast or pre-breakfast and pre-lunch regimen as management for GIH in a tertiary hospital setting.

We retrospectively evaluated all inpatients coprescribed prednisolone ≥7.5 mg and NovoMix30 for at least 48 hours over a 19-month period. BGLs were evaluated with repeated-measures analysis within four time periods across the day, beginning from the day prior to NovoMix30 administration.

A total of 53 patients were identified. NovoMix30 significantly reduced BGLs in the morning (mean 12.7 ± 4.5 vs. 9.2 ± 3.9 mmol/L, P < 0.001), afternoon (mean 13.6 ± 3.8 vs. 11.9 ± 3.8 mmol/L, P = 0.001) and evening (12.1 ± 3.8 vs. 10.8 ± 3.8 mmol/L, P = 0.01). With uptitration of insulin over 3 days, 43% of all BGLs were within the target range, compared with 23% on day 0 (P < 0.001). The final median dose of NovoMix30 was 0.15 (0.10-0.22) units/kg bodyweight, or 0.40 (0.23-0.69) units/mg of prednisolone, which is lower than our hospital guideline recommends. One overnight hypoglycaemic event was observed.

Mixed insulin as a pre-breakfast or pre-breakfast and pre-lunch regimen can target the hyperglycaemic pattern induced by prednisolone and minimise overnight hypoglycaemia. However, higher doses of insulin than those used in our study are likely required for optimal BGL control.