2.1. Study Design

The MASTER study [19] was a multicenter, randomized, parallel, open, three-armed, 24-week pilot study to assess the changes in plasma active and total levels of GLP-1 and GIP following mixed meal (460 kcal containing 56.5 g carbohydrates) ingestion at baseline and after the add-on treatment with either miglitol, sitagliptin, or a combination with miglitol plus sitagliptin for 24 weeks in Japanese T2D patients receiving diet therapy alone or taking metformin and/or sulfonylurea. Of the 49 T2D patients enrolled in the study from July 2011 to June 2012, 47 patients were randomly assigned to three treatment groups; miglitol (n = 15), sitagliptin (n = 16), and a combination with miglitol plus sitagliptin (n = 16). Finally, a total of 41 patients aged 40–78 years and treated with either miglitol (n = 14), sitagliptin (n = 14), or a combination with miglitol plus sitagliptin (n = 13) completed the study and their data were analyzed. In the present study, we performed a secondary analysis of data regarding SMI, TBFMI, iAUC of plasma aGLP-1 excursion (aGLP-1-iAUC), iAUC of plasma aGIP excursion (aGIP-iAUC), iAUC of plasma glucose excursion (glucose-iAUC), and iAUC of serum immunoreactive insulin (IRI) excursion (IRI-iAUC) following mixed meal ingestion at baseline and after 24-week add-on treatment with miglitol and/or sitagliptin in 35 T2D patients aged 40–78 years, whose SMI values were available in the MASTER study. The final sample consisted of 11 (9 males and 2 females), 13 (10 males and 3 females), and 11 (6 males and 5 females) T2D patients treated with miglitol, sitagliptin, or a combination with miglitol plus sitagliptin for 24 weeks, respectively. This study was approved by the Ethics Committees of Akita University (protocol code 2328, November 2019), and was performed in accordance with the Declaration of Helsinki. The MASTER study was registered in the University Hospital Medical Information Network (UMIN) clinical trials registry system (trial ID 000006098). Written informed consent was obtained from all participants prior to their participation.