Metformin × Prednisolone

Prednisolone (a systemic glucocorticoid) suppresses muscle glucose uptake and stimulates hepatic gluconeogenesis – steroid-induced diabetes develops or existing type 2 diabetes decompensates. Metformin offsets part of the effect but not all.

Hyperglycaemia: thirst, polyuria, fatigue, rising fasting glucose and HbA1c. With high prednisolone doses: decompensation risk with ketoacidosis in type 1 diabetes.

Monitor glucose 4 times daily during the first week of combination, then by self-monitoring. Increase metformin to maximum (2000–2500 mg/day) as needed. If decompensation occurs, add an α-glucosidase inhibitor, a GLP-1 receptor agonist, or temporary insulin.