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Long-Acting Insulin: Glargine and Detemir

Dec 1, 2025

Overview

This lecture explains key features of long-acting insulins (glargine and detemir), their clinical use, dosing pattern, and mixing rules.

Long-Acting Insulin Drugs

  • Long-acting insulins include glargine and detemir.
  • Cathedral insulation symbolizes insulin; long pieces represent long-acting duration.
  • Gargoyle in cathedral represents glargine; gargoyle sounds like glargine.
  • Determined detective represents detemir; detective sounds like detemir.
  • Glargine brand name in practice: Lantus; exams usually use generic name.
  • Detemir brand name in practice: Levemir; exams usually use generic name.

Long-Acting Insulin Summary Table

PropertyGlargineDetemir
TypeLong-acting insulinLong-acting insulin
Common brand nameLantusLevemir
Dosing frequencyUsually once daily, often eveningUsually once daily, often evening
PeakNo pronounced peakNo pronounced peak
Duration of actionAbout 24 hours (one day)About 24 hours (one day)
Mixing with other insulinCannot be mixed in same syringeCannot be mixed in same syringe

Pharmacologic Features and Clinical Use

  • Long-acting insulins are usually given once a day, typically in the evening.
  • They have no peak; they provide a slow, steady effect over about 24 hours.
  • They maintain a baseline insulin level in absence of meals or glucose spikes.
  • They counteract the natural rate of glucose release by the liver.
  • Most diabetics use combination therapy: long-acting for baseline control.
  • Rapid-acting insulins are added to manage blood glucose spikes after meals.

Administration and Mixing Rules

  • Long-acting insulins cannot be mixed in the same syringe with other insulins.
  • Each long-acting insulin dose must be drawn up in its own syringe only.
  • If both long-acting and rapid-acting insulin are needed, give two injections.
  • Using separate injections ensures each insulin works properly in the body.

Key Terms & Definitions

  • Long-acting insulin: Insulin formulation with slow onset and ~24-hour duration, no pronounced peak.
  • Glargine: Long-acting insulin (brand Lantus) used for baseline blood glucose control.
  • Detemir: Long-acting insulin (brand Levemir) used for baseline blood glucose control.
  • Basal insulin: Background insulin that controls blood glucose between meals and overnight.
  • Rapid-acting insulin: Insulin used to control blood glucose spikes associated with meals.