Basal insulin analogues in the management of diabetes mellitus: What progress have we made?

Insulin remains the most effective and consistent means of controlling blood glucose levels in diabetes. Since 1946, neutral protamine Hagedorn (NPH) has been the predominant basal insulin in clinical use. However, absorption is variable due to the need for resuspension and the time-action profile (peak activity 4-6 h after subcutaneous administration) confers an increased propensity for between-meal and nocturnal hypoglycaemia. In the 1980s, recombinant DNA technology enabled modifications to the insulin molecule resulting in the soluble long-acting insulin analogues, glargine and detemir. Both exhibit a lower risk of hypoglycaemia compared with neutral protamine Hagedorn due to improved time-action profiles and reduced day-to-day glucose variability. Glargine is indicated for administration once daily and detemir once or twice daily. Degludec is the latest prolonged-acting insulin which forms long subcutaneous multi-hexamers that delay absorption. Recent phase III trials in type 1 and type 2 diabetes show that degludec was non-inferior to comparators (predominantly glargine) with a minimal although inconsistent reduction in overall hypoglycaemia and a small absolute difference in nocturnal hypoglycaemia. Newer developmental agents include LY2605541 and glargine U300. LY2605541 comprises insulin lispro combined with polyethylene glycol, thereby increasing its hydrodynamic size and retarding absorption from the subcutaneous tissue. Glargine U300 is a new formulation of glargine resulting in a flatter and more prolonged time-action profile than its predecessor. This article reviews recent advances in basal insulin analogues, including a critical appraisal of the degludec trials.