There is a need for ideal basal insulin which can overcome the unmet need of a truly once daily insulin, with a flat peakless profile. Useful for all types of patients Insulin degludec is next generation insulin with a unique mode of protraction of forming soluble multi-hexamers and slow continuous absorption giving it a flat profile compared to the existing basal insulin. In patients with type 1 diabetes or with type 2 diabetes, at steady-state, the mean terminal half-life of insulin degludec was 25 hours, i.e., approximately twice as long as for insulin glargine (half-life of 12.1 hours). In once-daily dosing regimen it reaches steady state after approximately 3 days. The duration of action of insulin degludec was estimated to be beyond 42 hours in euglycaemic clamp studies and this gives the unique opportunity of flexible time dosing which is not an available option with the existing basal insulin. The glucose-lowering effect is evenly distributed across a 24-hour dosing interval with insulin degludec having 4 times lower variability than insulin glargine. This is an important attribute given the narrow therapeutic window of insulin and the goal of achieving night time and inter-prandial glycaemic control without increasing the risk for hypoglycaemia, a goal that is challenging given the variability of absorption and lower PK half-lives of current basal insulin products. The combination of the ultra-long, flat and stable profile with an improved hour-to-hour and day-to-day variability could present an improved risk-benefit trade-off with the lower risk of hypoglycaemia, allowing for targeting improved levels of glycaemic control.