Aims: To investigate the effect of sequential treatment escalation with empagliflozin and linagliptin on laboratory markers of α- and β-cell function in people with type 2 diabetes mellitus (T2DM) insufficiently controlled on metformin monotherapy.

Research design and methods: A total of 44 people with T2DM received 25 mg empagliflozin for a duration of 1 month in an open-label fashion (treatment period 1 [TP1]). Thereafter, they were randomized to a double-blind add-on therapy with linagliptin 5 mg or placebo (treatment period 2 [TP2]) for 1 additional month. α- and β-cell function was assessed using a standardized liquid meal test and an intravenous (i.v.) glucose challenge. Efficacy measures comprised the areas under the curve for glucose, insulin, proinsulin and glucagon after the liquid meal test and the assessment of fast and late-phase insulin release after an i.v. glucose load with a subsequent hyperglycaemic clamp.

Results: Empagliflozin reduced fasting and postprandial plasma glucose levels, associated with a significant reduction in postprandial insulin levels and an improvement in the conversion rate of proinsulin (TP1). The addition of linagliptin during TP2 further improved postprandial glucose levels, probably as a result of a marked reduction in postprandial glucagon concentrations (TP2). The insulin response to an i.v. glucose load increased during treatment with empagliflozin (TP1), and further improved after the addition of linagliptin (TP2).

Conclusion: After metformin failure, sequential treatment escalation with empagliflozin and linagliptin is an attractive treatment option because of the additive effects on postprandial glucose control, probably mediated by complementary effects on α- and β-cell function.