INS and type 2 diabetes mellitus: Direct costs – overall healthcare costs: Seven studies report healthcare costs for type 2 diabetes patients [51–57] for 23 different patient population ranging between €3717.22 for patients treated with metformin and sulfonylureas [56] and €15,299.46 in the year after insulin initiation for patients younger than 60 years of age [55] (Table 2, Fig. 3).