Determinants of excessive weight gain after the initiation of insulin therapy in type 2 diabetes mellitus: Retrospective inception cohort study (ZODIAC 60).

Aims: To explore determinants of excessive weight gain after initiation of insulin therapy in type 2 diabetes mellitus (T2DM), in particular variables identified in the pre-insulin phase.

Methods: We performed a retrospective observational intervention cohort study, by means of a new user design/ inception cohort concerning n = 5086 patients. We studied determinants of excessive weight gain (5 kg or more) in the first year after initiation of insulin therapy, using both visualization and logistic regression analysis with subsequent receiver operation characteristic (ROC) analyses. Potential determinants pre-, at- and post-insulin initiation were included.

Results: One out of 10 patients (10.0%) gained 5 kg weight or more. The earliest determinants of excessive weight gain were weight change (inversely) and HbA1c change in the two years prior to insulin therapy (p < 0.001). Patients that lost weight parallel with HbA1c rise in the two-years pre-insulin, showed the most pronounced weight gain. Of these patients, roughly one out of five (20.3%) gained 5 kg weight or more.

Conclusions: Clinicians and patients should be alert for excessive weight gain after initiation of insulin, in the case of weight loss prior to insulin therapy initiation, particularly with increasing and prolonged high HbA1c at (and after) insulin initiation.