Aims: The aim of this study is to examine the efficacy of adding a Dipeptidyl peptidase-4 (DPP-4) inhibitor to patients with type 2 diabetes inadequately controlled by metformin and sulphonylurea combination treatment. It has previously been reported that Asian patients may respond better to this class of agents1, so the response of Asian and non-Asian patients to this regimen was also examined.
Methods: The medical and computerized records of 80 patients were examined (M/F 51/29; Age 62.0 ± 9.3 yrs; Duration of Diabetes 12.7 ± 5.8 yrs; BMI 27.5 (25.2 – 31.8) kg/m2. These patients had baseline HbA1c levels from 7.0 to 12.5% and had a DPP-4 inhibitor added for a minimum period of 12 weeks to the combination of metformin and sulphonylurea. The primary endpoint was the change in HbA1c level before and after DPP-4 inhibitor treatment. Results are expressed as median and inter-quartile range or mean ± SD.
Results: During triple therapy, HbA1c fell from 8.3% (7.7-8.9) to 7.2% (6.8-7.6) (Z = 7.5; p < 0.0001, Wilcoxon signed rank test) and 26/80 patients achieved an HbA1c <7%. The magnitude of reduction in HbA1c did not decrease with longer duration of treatment. Poor baseline glycaemic control, lower BMI and younger age were shown by multiple regression to be associated with a better response, but duration of diabetes and gender did not affect outcome. There were 41 Asian patients (HbA1c 8.1%, 7.6-8.7) and 39 non-Asian patients (HbA1c 8.3%, 7.8-8.9) in this cohort. The HbA1c reduction was not different between the two groups [Asians -1.00% (0.6-1.3); non-Asians -0.90% (0.4-1.6)].
Conclusions: DPP-4 inhibitor as a third-line add-on therapy can achieve significant glycaemic improvement in patients with type 2 diabetes inadequately controlled on the combination of metformin and sulphonylurea. The improvement in HbA1c was similar between Asian and non-Asian patients.