Safety and efficacy of adding sitagliptin to insulin in patients with type 2 diabetes: The ASSIST-K study

Takai M, Ishikawa M, Maeda H et al.
Diabetes Res Clin Pract. 2014 Jan 6. doi: 10.1016/j.diabres.2013.12.045

Background

Diverse insulin regimens are employed in clinical practice to treat type 2 diabetes mellitus, because patient characteristics vary. The dipeptidyl peptidase-4 (DPP-4) inhibitor sitagliptin may be given in addition to insulin therapy.
Few studies have examined efficacy and safety of combined treatment [1-4]. This study addressed this issue by performing a retrospective multicenter study enrolling outpatients with T2DM with inadequate glycaemic control despite receiving insulin, who were treated with add-on sitagliptin for at least 6 months.

Main results

• HbA1c reduced from 8.7+1.3% to 8.3+1.2% (P<0.05) after 1 month of sitagliptin combination therapy, and to 8.0+1.3% at 3 months and 6 months (both P<0.05) after start of therapy.
• HbA1c was reduced by 1.1% 6 months after addition of sitagliptin therapy in the long-acting and once-daily insulin group, by 0.7% in the mixed and twice-daily group and in the mixed or rapid-acting and 3 times daily group, and 0.6% in the basal-bolus group. Percent reduction of HbA1c was significantly greater in the long-acting and once-daily insulin group than in the other insulin groups (P<0.05).
• Multiple regression analysis revealed that a higher baseline HbA1c was the main factor contributing to HbA1c reduction.
• Non-severe hypoglycaemia  symptoms occurred in 7.4% of all patients, without differences between the different insulin regimens.

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Conclusion

This study confirms the effect of the combination of sitagliptin and intensive insulin therapy, and shows lowering of HbA1c in all insulin regimes. HbA1c lowering was more effective in the long-acting and once-daily insulin groups, than with the other regimes. This may partly be explained by differences in baseline characteristics, although duration of insulin therapy, combined use of sulfonylureas and C-peptide levels were not relevant. Thus, adding sitagliptin to insulin therapy was useful in T2DM patients with poor glycaemic control, irrespective of the insulin regime.

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References

1. Vilsbøll T, Rosenstock J, Yki-Ja¨rvinen H, et al. Efficacy and safety of sitagliptin when added to insulin therapy in patients with type 2 diabetes. Diabetes Obes Metab 2010;12:167–77.
2. Kadowaki T, Tajima N, Odawara M, et al. Efficacy and safety of sitagliptin add-on therapy in Japanese patients with type 2 diabetes on insulin monotherapy. Diabetol Int )2013;(March) [Epub ahead of print].
3.Hong ES, Khang AR, Yoon JW, et al. Comparison between sitagliptin as add-on therapy to insulin and insulin dose-increase therapy in uncontrolled Korean type 2 diabetes: CSI study. Diabetes Obes Metab 2012;14(9):795–802.
4.Katsuno T, Ikeda H, Ida K, et al. Add-on therapy with the DPP-4 inhibitor sitagliptin improves glycemic control in insulin-treated Japanese patients with type 2 diabetes mellitus. Endocr J )2013;(February) [Epub ahead of print].