Evaluation of vildagliptin and fixed dose combination of vildagliptin and metformin on glycemic control and insulin dose over three months in patients with type 2 diabetes mellitus'.

Sir,

This letter is in response to the interesting study published by Ved and Shah titled – ‘Evaluation of vildagliptin and fixed dose combination of vildagliptin and metformin on glycemic control and insulin dose over three months in patients with type 2 diabetes mellitus’.

Incretin based therapy are the new effective innovation in the treatment of diabetes. We thank Dr. Paresh Ved and Dr. Samrat Shah for sharing the finding of this multicenter study with us but this study raised a few questions which were left unanswered. First of all, how many patients received vildagliptin vs FDC combination of vildagliptin and metformin? Secondly, how was the dose titrated upwards for them? Did the clinician follow a protocol across all the centers? Was there a significant difference in HbA1c drop/FPG/PPG change in all the three groups? Also, they reported weight loss as one of the benefit of using DPP-IV inhibitors. In a recent meta-analysis[1] and a randomized trial[2] they have been found to be weight neutral. If the weight change associated with concurrent metformin use, was not clarified in the study. Lastly, there were no comments on the adverse events seen in each group separately.

As the authors mentioned, elderly patient may be better candidate for such therapy as they have lower risk of hypoglycemia.[3] However, they also tend to have higher incidence of renal dysfunction which requires very careful selection. This study supports the findings that both drugs execute complimentary actions achieving better glycemic control.[45] Recently FDA also approved use of exenatide in combination with long acting insulin based on a study published by Buse et al.[6]

We definitely need more randomized trials to further elucidate the role of DPP-IV inhibitors and their benefit in terms of cardiac, lipids and insulin sensitivity as mentioned by the authors.