Preliminary remarks on Insulins

Insulin categories

Insulin is available in two main forms: human insulin and analogues of human insulin.

Human insulin is a synthetic version of insulin that exactly replicates the structure of natural insulin. However, when injected under the skin, it differs from natural insulin in that it tends to aggregate and has a longer absorption time.

Insulin analogues are also synthetic insulins designed to closely mimic the body's natural insulin release. The amino acid sequence of insulin analogues is altered compared to human insulin to modify its pharmacokinetic properties. Once absorbed, it works similarly to human insulin but with more predictable absorption. Insulin analogues are more expensive than human insulin.

Insulin characteristics

Insulins are classified based on their action profile, which include:

  • Onset of action: the time it takes for insulin to start acting
  • Peak action: the at which insulin reaches its maximum effectiveness
  • Duration of action: the length of time the insulin remains effective

Insulin types

Insulin types are generally categorised into three main groups: Rapid-acting (or short-acting), Intermediate-acting, and Long-acting.

Rapid-acting insulin (or Short-acting)

  • Rapidly absorbed from fat tissue (subcutaneous) into the bloodstream.
  • Intended to provide the necessary bolus or prandial insulin.
  • Used to control blood glucose levels during meals, snacks, and to correct hyperglycaemia.

Includes:

Regular Human Insulin

  • Onset: approx. 30 min
  • Peak: in 2 to 4 hours
  • Duration: 6 to 8 hours
  • The higher the dose, the faster the onset, but the longer the time to peak and the longer the duration of effect.
  • Less predictable than rapid-acting insulin analogues.
  • Administered at least 30 minutes before meals to reduce postprandial glucose levels.
  • Examples: Actrapid®, Humulin R®

(Ultra-) Rapid-Acting Insulin Analogues (insulin Aspart, insulin Lispro, insulin Glulisine)

  • Onset: 5 to15 minutes
  • Peak: in 1 to 2 hours
  • Duration: 4 to 6 hours
  • Regardless the dose, the onset and peak time remain similar.
  • The duration of action varies with the dose: few units may last 4 hours or less, while a larger dose (25 or 30 units) may last 5 to 6 hours. As a general rule, these insulins are considered to have a duration of action of 4 hours.
  • Administered during meals to correct high blood glucose levels.
  • Examples: Humalog® (insulin Lispro), Novorapid/® (insulin Aspart), Apidra® (insulin Glulisine)

Intermediate-acting insulin

  • Absorbed more slowly, with a longer duration of action.
  • Intended to provide the necessary basal insulin (when administered at bedtime) or prandial insulin (when administered in the morning).
  • Used to control blood glucose levels between meals and overnight.

Includes:

Isophane (NPH) Human Insulin

  • NPH : Neutral Protamine Hagedornis
  • A fish protein, protamine, has been added to regular human insulin to delay its absorption. As NPH is a suspension of different sized crystals, its absorption and action time are highly unpredictable.
  • Onset: 1 to 2 hours
  • Peak: in 4 to 12 hours
  • Duration: 14 to 18 hours
  • A small dose given before meals results in an earlier peak and shorter duration of action (to cover needs between meals), while a higher dose given at bedtime will have a longer peak effect and a longer duration of action.
  • Examples: Insulatard®, Humulin N®

Premixed Insulin (or Biphasic insulin)

  • NPH premixed with regular human insulin or rapid-acting insulin analogs.
  • Combines the action profile of rapid-acting and intermediate-acting insulins:
    • Onset: 30 to 60 minutes
    • Peak: in 2 to 8 hours
    • Duration: 10 to 16 hours
  • Includes various combinations:
    • NPH mixed with regular human insulin in a 70:30 ratio (70% NPH, 30% Regular). e.g. Mixtard 30®
    • NPH mixed with rapid-acting insulin analogue Lyspro in a 75:25 ratio (75% NPH, 25% insulin Lyspro). e.g. Humalog Mix 75/25®
    • NPH mixed with rapid-acting insulin analogue Aspart in a 70:30 ratio (70% NPH, 30% Aspart). e.g. NovoMix 30®

Long-acting insulin (or Prolonged-acting)

  • Absorbed slowly, with minimal peak and a stable, prolonged effect lasting from 8 to 24 hours.
  • Intended to provide basal insulin needed throughout the day, especially at night.
  • Used to control blood glucose levels overnight, while fasting, and between meals.

Includes:

Long-acting insulin analogues (Glargine insulin, Detemir insulin, Degludec insulin)

  • Onset: 3 to 6 hours (for Glargine insulin)
  • Peak: over the next few hours
  • Duration: relatively stable for 12 to 24 hours with Detemir insulin and 24 hours for Glargine insulin
  • Examples: Levemir® (Detemir insulin), Lantus® (Glargine insulin), Tresiba® (Degludec insulin, ultra-long-acting)

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Storage

Any unopened insulin container should be stored in a refrigerator between 2°C and 8°C.

Once in use, Insulin vials or pens can be kept at room temperature, between 15°C and 30°C, for approximatively 1 month. Insulin detemir can be stored at room temperature for up to 42 days.

Do not freeze insulin and protect it from light.

Exposure to high temperatures can reduce insulin efficacy and compromise glycaemia control.

Regular insulin, basal insulin analogues (such as glargine, detemir, and degludec), and rapid-acting insulin analogues (such as lispro, aspart, and glulisine) are clear and colourless. They should not be used if they appear cloudy or viscous.

Insulin therapy

Insulin doses are expressed in units.

It is not recommended to switch a patient from one type of insulin to another. Changes in concentration, brand (manufacturer), type, origin (human insulin or human insulin analogue), and/or method of manufacture may require adjusting the dose.

Insulin is administered by subcutaneous injection using either a syringe marked with insulin units and a needle, or a pre-filled pen. Insulin pumps are not par of MSF Standard.

For pre-filled pens, only use specific needles designed for theses types of pen.

MSF codes and labels for insulins

All insulins have a concentration of 100 IU/ml, as indicated on the label (but not in the code).

  • Type of insulin
    • DINJINSA+++: analogue insulin
    • DINJINSH+++: human insulin
  • Duration of action
    • B = biphasic: the ratio is identified in the label: fast / long-acting
    • L = long-acting analogue insulin
    • U = ultra-rapid analogue insulin
    • I = intermediate / isophane human insulin
    • R = rapid-acting human insulin
  • Volume / Quantity
    • 1 = 10 ml
    • 3 = 3 ml
  • Insulin presentation:
    • V: 10 ml vial
    • C: 3 ml cartridge, for use with a reusable auto-injector
    • AP: 3 ml pre-filled pen (single-use insulin pen)
  • Manufacturer: last letter of code and label
    • L = Lilly
    • N = Novo Nordisk
    • S = Sanofi