In a randomised trial that aimed to assess the efficacy of a smart insulin pen cap for the management of individuals with suboptimally controlled type 2 diabetes (intervention group: feedback and alarm notifications; control group: masked device without alarm notifications), compared with the control group (n=40), the intervention group (n=40) experienced a greater HbA1c reduction (−0.98 pp [–10 mmol/mol] vs −0.72 pp [–7 mmol/mol]; p=0.006) and lower blood glucose levels (8.2 ± 1.9 vs 8.7 ± 2.3 mmol/l [147.0 ± 34 vs 157.6 ± 42 mg/dl]; p<0.01). This evidence concerns the gene INS and type 2 diabetes mellitus.