Effectiveness of insulin therapy in people with Type 2 diabetes in the Hoorn Diabetes Care System

Aims To identify HbA1c trajectories after the start of insulin treatment and to identify clinically applicable predictors of the response to insulin therapy. Methods The study population comprised 1203 people with Type 2 diabetes included in the Hoorn Diabetes Care System (n = 9849). Inclusion criteria were: age ≥ 40 years; initiation of insulin during follow‐up after failure to reach HbA1c levels ≤ 53 mmol/mol (7%) with oral glucose‐lowering agents; and a follow up ≥ 2 years after initiating insulin. Latent class growth modelling was used to identify trajectories of HbA1c. Subjects considered to be ‘off target’ had HbA1c levels ≥ 53 mmol/mol (7.0%) during one‐third or more of the follow‐up time, and those considered to be ‘on target’ had HbA1c levels ≥ 53 mmol/mol (7.0%) during less than one‐third of the follow‐up time. Results Four HbA1c trajectories were identified. Most people (88.7%) were classified as having a stable HbA1c trajectory of ~57 mmol/mol (7.4%). Only 24.4% of the people were on target in response to insulin; this was associated with lower HbA1c levels and a higher age at the start of insulin treatment. Conclusions Using latent class growth modelling, four HbA1c trajectories were identified. A quarter of the people starting insulin were on target. Low HbA1c levels and advanced age at the start of insulin therapy were associated with better response to insulin therapy. Initiating insulin earlier improves the likelihood of achieving and sustaining glycaemic control. What's new? We showed the difficulties in reaching and sustaining a target HbA1c of ≤ 53 mmol/mol (7.0%) in the majority of people with Type 2 diabetes, even in a centrally organized managed diabetes care system. Of the 1203 people initiating insulin therapy, 294 people (24.4%) were ‘on target’, whereas 909 people (75.6%) were ‘off target’ with an equal follow‐up of 5.5 years. This study suggests that initiating insulin earlier increases the likelihood of achieving and sustaining glycaemic control.