Identifying Incident Diabetes Cases in Denmark

We identified incident diabetes cases based on the National Patient Registry^{30 (link)} and the National Prescription Registry,^{31 (link)} using an algorithm developed by the Danish Health Data Agency for the purpose of monitoring diabetes prevalence and incidence in Denmark.³² This algorithm has been used in various register-based studies based on the Danish population.^{33 (link),34 (link)}The Prescription Registry holds information on all dispensed drugs. We defined T2D cases as persons with two contacts with a pharmacy [Anatomical Therapeutic Chemical system (ATC) codes A10B (blood glucose–lowering drugs, excluding insulins), though excluding A10BJ02 (liraglutide: only Saxenda®), as well as A10AE54 (insulin glargine and lixisenatide) and A10AE56 (insulin degludec and liraglutide)] and/or T2D-related hospital contacts (International Classification of Diseases (ICD) 8 code 250 or ICD10 code E11). We defined a person as case from the second register record. A diagnosis of type 1 diabetes [ICD-8 code 249 or ICD-10 code E10 and/or at least one dispensed prescription with ATC A10A (insulins and analogs), excluding A10AE54 (insulin glargine and lixisenatide) and A10AE56 (insulin degludec and liraglutide)] resulted in censoring (exclusion if before baseline). All persons with a diagnosis of T2D before baseline (identified as described above for incident cases) were excluded.