Efficacy and safety of insulin degludec in a flexible dosing regimen vs insulin glargine in patients with type 1 diabetes (BEGIN: Flex T1): a 26-week randomized, treat-to-target trial with a 26-week extension

J Clin Endocrinol Metab. 2013 Mar;98(3):1154-62. doi: 10.1210/jc.2012-3249. Epub 2013 Feb 7.


Objective: This study investigated the efficacy and safety of insulin degludec (IDeg) once daily (OD), varying injection timing day to day in subjects with type 1 diabetes.

Research design and methods: This 26-week, open-label, treat-to-target, noninferiority trial compared IDeg forced flexible (Forced-Flex) OD (given in a fixed schedule with a minimum 8 and maximum 40 hours between doses) with IDeg or insulin glargine (IGlar) given at the same time daily OD. In the 26-week extension, all IDeg subjects were transferred to a free-flexible (Free-Flex) regimen, which allowed any-time-of-day dosing, and compared with subjects continued on IGlar.

Results: After 26 treatment weeks, mean glycosylated hemoglobin was reduced with IDeg Forced- Flex (-0.40%), IDeg (-0.41%), and IGlar (-0.58%). IDeg Forced-Flex noninferiority was achieved. Fasting plasma glucose reductions were similar with IDeg Forced-Flex and IGlar but greater with IDeg (-2.54 mmol/L) than IDeg Forced-Flex (-1.28 mmol/L) (P = .021). At week 52, IDeg Free-Flex subjects had similar glycosylated hemoglobin but greater fasting plasma glucose reductions than IGlar subjects (-1.07 mmol/L) (P = .005). Confirmed hypoglycemia rates (plasma glucose <3.1 mmol/L or severe hypoglycemia) were similar at weeks 26 and 52. Nocturnal confirmed hypoglycemia was lower with IDeg Forced-Flex vs IDeg (37%; P = .003) and IGlar (40%; P = .001) at week 26 and 25% lower with IDeg Free-Flex vs IGlar (P = .026) at week 52.

Conclusions: IDeg can be administered OD at any time of day, with injection timing varied without compromising glycemic control or safety vs same-time-daily IDeg or IGlar. This may improve basal insulin adherence by allowing injection-time adjustment according to individual needs.

Trial registration: ClinicalTrials.gov NCT01079234.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Blood Glucose / drug effects
  • Diabetes Mellitus, Type 1 / drug therapy*
  • Dose-Response Relationship, Drug
  • Drug Administration Schedule
  • Female
  • Glycated Hemoglobin / metabolism
  • Humans
  • Hypoglycemic Agents / administration & dosage*
  • Hypoglycemic Agents / adverse effects
  • Insulin Glargine
  • Insulin, Long-Acting / administration & dosage*
  • Insulin, Long-Acting / adverse effects
  • Male
  • Middle Aged
  • Self Administration
  • Treatment Outcome


  • Blood Glucose
  • Glycated Hemoglobin A
  • Hypoglycemic Agents
  • Insulin, Long-Acting
  • hemoglobin A1c protein, human
  • Insulin Glargine
  • insulin degludec

Associated data

  • ClinicalTrials.gov/NCT01079234