New medicines are often expensive and have a risk–benefit ratio that has not been fully elucidated yet.1,2 Therefore, clinical guidelines usually do not recommend their use, especially if less expensive and evidence-based alternatives are available.3 This is also reflected in the most current type 2 diabetes mellitus (T2DM) guidelines, which do not recommend the use of insulin glargine 300 U/mL and insulin degludec.4–6 These two most recently introduced long-acting insulins, further referred to as ‘newer insulins’, gained market access in 2013 and 2015, respectively. This evidence concerns the gene INS and diabetes mellitus.