Results

Seventy-seven patients entered the study (linagliptin: 61; placebo: 16). Four patients withdrew prematurely. There was little evidence of linagliptin accumulation. Exposure, maximum and trough plasma concentrations of linagliptin increased less than dose-proportionally. Rapid and sustained inhibition of dipeptidyl peptidase-4 reached 91-93% across linagliptin doses at steady state. At the end of the 24-h dosing interval, inhibition was still high (82-90%). There were marked increases in plasma glucagon-like peptide-1 after 28 days of dosing. Compared to placebo, all linagliptin doses resulted in statistically significant decreases of the area under the glucose curve following a meal tolerance test on day 29, that is, 24 h after the last study drug intake. After 28 days of treatment with linagliptin the placebo-corrected mean change in haemoglobin A1c (HbA1c) (median baseline 7.0%) was -0.31% (2.5-mg dose), -0.37% (5-mg dose) and -0.28% (10-mg dose). The frequency of adverse events was similar for linagliptin (31%) and placebo (34%). There were no notable safety concerns.

Conclusions

Linagliptin administration led to attenuation of postprandial glucose excursions and, despite a low HbA1c at baseline, statistically significant reductions in HbA1c after only 4 weeks of treatment. Linagliptin had a safety and tolerability profile similar to placebo in T2DM patients.