The Dutch guideline considers NPH-insulin as the first choice with insulin glargine 100 U/mL and insulin detemir as potential alternatives in specific situations.5 Although adherence to guidelines is generally high among Dutch GPs,8,9 the popularity of insulin glargine 300 U/ml and insulin degludec in Dutch practice is rapidly increasing.10 However, little is known about patterns of newer insulin use in patients with T2DM and especially information on practice variation and practice- and patient-related characteristics associated with the prescription of newer long-acting insulins is lacking. This evidence concerns the gene INS and type 2 diabetes mellitus.