INS and type 2 diabetes mellitus: We defined type 2 diabetes from register-based data as at least one registration of type 2 diabetes diagnosis and use of non-insulin glucose-lowering drugs, or two registrations if individuals were not treated with non-insulin glucose-lowering drugs (either E11 diagnosis code from specialist care (ICD-10) or T90 diagnosis code from the primary care database [ICPC-2]).