Changing to basal-bolus insulin therapy for the inpatient management of hyperglycemia—a natural experiment

Objective: Most acute-care hospitals have transitioned from sliding-scale to basal-bolus insulin therapy to manage hyperglycemia during hospitalization, but there is limited scientific evidence demonstrating better short-term clinical outcomes using the latter approach. The present study sought to determine if using basal-bolus insulin therapy favorably affects these outcomes in noncritical care settings and, if so, whether the magnitude of benefit differs in patients with known versus newly diagnosed type 2 diabetes. Methods: This natural experiment compared outcomes in 10,120 non–critically ill adults with type 2 diabetes admitted to an academic teaching hospital before and after hospital-wide implementation of a basal-bolus insulin therapy protocol. A group of 30,271 inpatients without diabetes (type 1 or 2) served as controls. Binomial models were used to compare percentages of patients with type 2 diabetes who were transferred to intensive care, experienced complications, or died in the hospital before and after implementation of the protocol, controlling for changes in the control group. The analysis also evaluated before-after changes in length of stay and glucometric indicators. Results: Implementation of basal-bolus therapy did not reduce intensive care use (the primary outcome), complications, mortality, or median length of stay, except in patients with newly diagnosed diabetes (n = 234), who experienced a statistically significant decline in the incidence of complications (P<.01). The absence of effect in previously diagnosed patients was observed in spite of a 32% decline (from 3.7% to 2.5%) in the proportion of inpatient days with hypoglycemia <70 mg/dL (P<.01) and a 16% decline (from 13.5% to 11.3%) in the proportion of days with hyperglycemia >300 mg/dL (P<.01). Conclusion: Despite achieving significant reductions in both hyperglycemia and hypoglycemia, use of basal-bolus insulin therapy to manage hyperglycemia in non–critically ill hospitalized patients did not improve short-term clinical outcomes, except in the small minority of patients with newly diagnosed diabetes. The optimal management of hyperglycemia for improving these outcomes has yet to be determined.