Geospatial distribution of the adoption of dipeptidyl-peptidase-4 inhibitors for type 2 diabetes among Medicare beneficiaries

Objective: To characterize the geospatial distribution of the adoption of dipeptidyl-peptidase-4 inhibitor (DPP-4i) antidiabetics versus second generation sulfonylureas (SU). Methods: Using Medicare claims data 2012-2017, two cohorts were built with new-users of either sitagliptin or saxagliptin each versus active comparator SU. For each ZIP Code tabulation area (ZCTA), the proportion DPP-4i prescribing was used in a local indicator of spatial association hotspot analysis. Multilevel logistic models were used to quantify the variation in medication use at the individual, ZCTA, state, and region levels. Results: DPP-4i utilization proportion was low (sitagliptin median = 0.22; interquartile range 0.15 to 0.33; saxagliptin median = 0.025; 0.00 to 0.069). Clustering was observed for sitagliptin (Moran's I = 0.32) and saxagliptin (Moran's I = 0.20). States and ZCTAs accounted for 8.1 % and 13.3 % of variation in sitagliptin and saxagliptin prescribing, respectively. Conclusions: Variation across ZCTAs suggests neighborhood factors may be important determinants of prescribing.