Steroid‐induced hyperglycemia (SIHG) has shown to independently increase the risk for mortality in patients with acute graft‐versus‐host disease, and it is still unclear whether SIHG might be a modifiable risk factor. Therefore, a feasibility trial was carried out aiming to evaluate the performance of a standardized decision support system (GlucoTab [GT]) for insulin therapy in patients with SIHG. A total of 10 hyperglycemic acute graft‐versus‐host disease patients were included and treated either with GT or standard of care during hospitalization. Follow‐up duration was 6 months. Comparing the GT versus standard of care group, 364 versus 1,020 glucose readings were available during a median of 41 days (interquartile range [IQR] 22–89) and 101 days (IQR 55–147) of hospitalization. The median overall glucose levels were 151 mg/dL (123–192) versus 162 mg/dL (IQR 138–193) for GT and standard of care, respectively (P < 0.001); hypoglycemia rates were comparably low. Treatment of SIHG with an algorithm‐based system for subcutaneous insulin was feasible and safe. We performed a trial investigating the feasibility and safety of a mobile algorithm based decision support system (GlucoTab) in the treatment of steroid‐induced hyperglycemia in patients with acute Graft‐versus‐host disease (GvHD). As retrospective data indicated that steroid‐induced hyperglycemia is a predictor for adverse outcome in this depicted cohort of patients with GvHD we demonstrate that hyperglycemia might be improved by using such a decision support system. Furthermore GlucoTab might serve as a tool for a larger study to investigate whether glucose is just a rigid marker for severe disease or might be a modifiable risk factor of poor outcome. [ABSTRACT FROM AUTHOR]