Starting Insulin in Type 2 Diabetes: Real-World Outcomes After the First 12 Months of Insulin Therapy in a New Zealand Cohort

Currently, there is no consensus on which form of insulin to use when initiating insulin in type 2 diabetes (T2D). Our aim was to compare glycated hemoglobin (HbA1C) reduction, weight change and severe hypoglycemia rates during the first year after initiation of intermediate-acting insulin isophane, insulin glargine and pre-mixed insulin in patients with T2D.

Electronic clinical records of patients with T2D, starting insulin at a tertiary referral center in Auckland, New Zealand, from January 1 to December 31, 2012, were retrospectively evaluated. Primary outcomes were HbA1C reduction at 12 months and number of hospital admissions for hypoglycemia.

Of 339 eligible patients, 273 (80.5%) started on intermediate insulin, 24 started on insulin glargine and 42 started on pre-mixed insulin. The mean HbA1C at insulin initiation was 89–95 mmol/mol, but had decreased at 12 months by 26.6 mmol/mol with insulin glargine, 23.4 mmol/mol with pre-mixed insulin and 16.6 mmol/mol with insulin isophane (p < 0.05 vs. baseline for all groups). Patients on insulin glargine were more likely to achieve the HbA1C target of <55 mmol/mol compared with patients on insulin isophane (16.7% vs. 4.8%; p = 0.04). Persistence rates were higher in patients initiated on pre-mixed insulin vs. insulin isophane (90.5% vs. 69.6%; p = 0.01). After controlling for confounding variables, glargine was more likely to achieve an HbA1C target of <55 (p = 0.05).

All insulin types caused a significant reduction in HbA1C, but very few met HbA1C targets. Insulin isophane was the most common type of insulin prescribed at initiation, with comparable outcomes to other types of insulin. More observational studies are needed to explore the possible impact of using other insulin types at initiation.