Therapeutic inertia is one of the leading causes of suboptimal glycaemic control.<h4>Aim</h4>To assess the degree of inertia in insulin initiation and intensification in people with Type 2 diabetes mellitus (DM-2).<h4>Methods</h4>We performed a retrospective longitudinal cohort study and followed DM-2 2 years before and 2 years after the start of insulin. This evidence concerns the gene INS and diabetes mellitus.