Insulin degludec, an ultra-longacting basal insulin, versus insulin glargine in basal-bolus treatment with mealtime insulin aspart in type 2 diabetes (BEGIN Basal-Bolus Type 2): a phase 3, randomised, open-label, treat-to-target non-inferiority trial

Background: Basal insulin therapy does not stop loss of β-cell function, which is the hallmark of type 2 diabetes mellitus, and thus diabetes control inevitably deteriorates. Insulin degludec is a new, ultra-longacting basal insulin. We aimed to assess efficacy and safety of insulin degludec compared with insulin glargine in patients with type 2 diabetes mellitus.

Methods: In this 52 week, phase 3, open-label, treat-to-target, non-inferiority trial, undertaken at 123 sites in 12 countries, we enrolled adults (aged ≥18 years) with type 2 diabetes mellitus and a glycated haemoglobin (HbA(1c)) of 7·0-10·0% after 3 months or more of any insulin regimen (with or without oral antidiabetic drugs). We randomly allocated eligible participants in a 3:1 ratio to receive once-daily subcutaneous insulin degludec or glargine, stratified by previous insulin regimen, via a central interactive response system. Basal insulin was titrated to a target plasma glucose concentration of 3·9-<5·0 mmol/L self-measured before breakfast. The primary outcome was non-inferiority of degludec to glargine measured by change in HbA(1c) from baseline to week 52 (non-inferiority limit of 0·4%) by ANOVA in the full analysis set. We assessed rates of hypoglycaemia in all treated patients. This study is registered with ClinicalTrials.gov, number NCT00972283.

Findings: 744 (99%) of 755 participants randomly allocated degludec and 248 (99%) of 251 allocated glargine were included in the full analysis set (mean age 58·9 years [SD 9·3], diabetes duration 13·5 years [7·3], HbA(1c) 8·3% [0·8], and fasting plasma glucose 9·2 mmol/L [3·1]); 618 (82%) and 211 (84%) participants completed the trial. After 1 year, HbA(1c) decreased by 1·1% in the degludec group and 1·2% in the glargine group (estimated treatment difference [degludec-glargine] 0·08%, 95% CI -0·05 to 0·21), confirming non-inferiority. Rates of overall confirmed hypoglycaemia (plasma glucose <3·1 mmol/L or severe episodes requiring assistance) were lower with degludec than glargine (11·1 vs 13·6 episodes per patient-year of exposure; estimated rate ratio 0·82, 95% CI 0·69 to 0·99; p=0·0359), as were rates of nocturnal confirmed hypoglycaemia (1·4 vs 1·8 episodes per patient-year of exposure; 0·75, 0·58 to 0·99; p=0·0399). Rates of severe hypoglycaemia seemed similar (0·06 vs 0·05 episodes per patient-year of exposure for degludec and glargine) but were too low for assessment of differences. Rates of other adverse events did not differ between groups.

Interpretation: A policy of suboptimum diabetes control to reduce the risk of hypoglycaemia and its consequences in advanced type 2 diabetes mellitus might be unwarranted with newer basal insulins such as degludec, which are associated with lower risks of hypoglycaemia than insulin glargine.

Funding: Novo Nordisk.