11/13/24, 7\:43 PM Guide | Insulin prescribing

Insulin prescribing

Table of contents

Introduction

Insulin is a polypeptide hormone produced by the pancreatic beta cells. It promotes glucose uptake in adipose tissue and
muscles while inhibiting glucose release from the liver, lowering blood glucose levels to prevent hyperglycaemia and its
related complications.
Proper insulin prescribing requires understanding the di
considerations such as insulin management during surgery.
This guide provides a comprehensive overview of the sources of insulin, types of preparations, insulin regimens, key
prescribing considerations, insulin use during surgery, and potential side e

Sources of insulin

Insulin is derived from various sources\:
1
Human insulin\: manufactured through recombinant DNA technology; this is the most commonly used form of insulin
Human analogue insulins\: modi
aspart, and insulin glargine)
Animal-derived insulin\: porcine (pig-derived) or bovine (beef-derived) insulin. Porcine insulin is structurally closer to human
insulin, while beef insulin has a longer duration of action.
Animal-derived insulin
These older forms of insulin are no longer initiated in those with diabetes, although some patients may still use these
regimes. These types may be preferred by patients with allergic reactions to synthetic insulins or for personal reasons.
If prescribing these forms of insulin, always check with a pharmacist to ensure the correct prescription and that the insulin
is available within your hospital.

Insulin preparations

In the body, insulin secretion has two primary phases\: basal insulin, which provides a steady background level to manage
continuous glucose release from the liver, and meal-time bolus insulin, which is released in response to glucose from food
and drink.
Insulin preparations are classi
according to patient needs.

Rapid-acting insulin

Rapid-acting insulin analogues are designed for rapid action with an onset of 15 minutes and last for 2-5 hours. 2-3
These
should be injected immediately before meals. They are ideal for managing postprandial glucose levels and are commonly used
in basal-bolus regimens or continuous subcutaneous insulin infusion (CSII).
https\://app.geekymedics.com/osce-guides/prescribing/insulin-prescribing/ 1/511/13/24, 7\:43 PM Guide | Insulin prescribing
Examples include\:
Humalog (insulin lispro)
Novorapid (insulin aspart)

Short-acting insulin

Short-acting or soluble insulins take a longer time to act than rapid-acting insulins, with an onset of 30-60 minutes, peaking at
1-4 hours, and lasting up to 9 hours. 2-3
These are typically injected subcutaneously around 15 to 30 minutes before eating
when used in the basal-bolus regimen. 3
They can also be administered intravenously for an instant e
as diabetic ketoacidosis (DKA) or during surgery.
Examples include\:
Actrapid (human soluble insulin)

Intermediate-acting insulin

Intermediate-acting insulins provide longer-lasting glucose control. They are designed to mimic the e
basal insulin. Their onset is 1-2 hours, peak at 3-12 hours, and last for 11-24 hours. 2-3
These insulins are often used in twice-
daily regimens or mixed preparations.
Examples include\:
Humulin I (isophane insulin)

Long-acting insulin

Long-acting insulins’ action can last for up to 36 hours, and they achieve a steady-state level after 2-4 days to produce
constant insulin levels. 2-3
These are typically used as the basal component in basal-bolus regimens.
Examples include\:
Lantus/Toujeo (insulin glargine)
Levemir (insulin detemir)
Tresiba (insulin degludec)

Mixed preparations (biphasic insulins)

Mixed preparations combine short-acting and intermediate-acting insulin to cover both basal and postprandial glucose
levels in fewer injections. 2-3
They are often used in twice-daily regimens.
In mixed preparation regimens, carbohydrate intake is usually matched to the insulin dose, whereas in multiple injection
regimens, patients adjust their insulin doses based on their carbohydrate intake.
Examples include\:
Humalog Mix 25 (25% insulin lispro, 75% insulin lispro protamine)
NovoMix 30 (30% insulin aspart, 70% insulin aspart protamine)

Insulin regimens

Once or twice-daily regimens

These regimens involve long-acting or mixed insulins, with injections administered at set times, providing both basal and
postprandial glucose control.
These regimens may be used in those with type 2 diabetes who are newly started on insulin or when dependent on others to
administer their insulin.
4

Basal-bolus regimens

A basal-bolus regimen mimics the body’s natural insulin secretion. Long-acting insulin (basal) is given once daily to maintain
steady glucose levels between meals, while rapid- or short-acting insulin (bolus) is administered before meals to control
postprandial spikes.
Patients adjust their insulin doses based on their carbohydrate intake, o
4
https\://app.geekymedics.com/osce-guides/prescribing/insulin-prescribing/ 2/511/13/24, 7\:43 PM Guide | Insulin prescribing

Continuous subcutaneous insulin infusion (CSII)

CSII provides continuous delivery of rapid-acting insulin, with patient-controlled boluses at mealtimes. CSII allows for precise
control of blood sugar levels and o
This therapy is mainly used in patients with type 1 diabetes who\:
5
Experience recurrent, unpredictable hypoglycaemia
Have an HbA1c persistently above 64 mmol/mol (8.5%) despite multiple daily injections
Are under 12 years of age, where multiple injections are impractical
It is recommended that children using CSII attempt multiple injection regimens again between the ages of 12 and 18, as this is
the standard approach to insulin therapy.

Insulin administration

Insulin is typically administered subcutaneously in the abdomen, thighs, upper arms, or buttocks. Absorption rates can vary by
20-40% depending on the site and time of day, with the abdomen generally providing the fastest absorption.
To avoid complications like lipohypertrophy, patients should rotate injection sites regularly.
In urgent situations, such as during surgery, or in severe illness, insulin can be administered intravenously for rapid blood
glucose control.

Insulin and surgery

Managing insulin during surgery requires careful planning to maintain stable blood glucose levels. Local protocols should be
followed, as these may di

Minor procedures

For patients with good glycaemic control (HbA1c \< 69 mmol/mol or 8.5%) undergoing minor procedures (surgeries where less
than one meal will be missed, e.g. outpatient procedures), on the day before surgery, insulin should be administered as usual,
except for long-acting analogues, where the dose should be reduced by 20%. 6
If the patient usually takes their basal insulin in
the morning, the reduced dose should be given instead on the morning of surgery.
7

Major procedures

Patients undergoing major procedures (surgeries with a long fasting period where more than one meal is missed, e.g.
knee/hip replacement surgeries) or patients with poorly controlled diabetes will typically require a variable-rate intravenous
insulin infusion (VRIII), using human soluble insulin. 6
The goal is to maintain blood glucose levels within a target range
(typically 6–10 mmol/L).
In emergency surgeries, blood glucose, ketone levels, and electrolytes must be checked before surgery. If signs of
ketoacidosis are present, treatment protocols for DKA should be initiated, and surgery should be postponed if feasible.
6
Before surgery
usual.
2
Long-acting insulin dose should be reduced by 20% the day before surgery. Otherwise, insulin should be administered as
During surgery
On the morning of the surgery, long-acting insulin should continue to be administered at 80% of the usual dose, and all other
subcutaneous insulin withheld.
2
A VRIII should be started alongside a glucose and potassium infusion. Potassium is essential because insulin drives potassium
into cells, which can lead to hypokalaemia (low potassium levels), increasing the risk of cardiac arrhythmias.
Blood glucose levels should be monitored hourly, and the VRIII adjusted depending on the result.
After surgery
Short-acting or pre-mixed insulin can be restarted once the patient can eat and drink, when the next meal-related dose is due.
The VRIII and glucose/potassium solution should be continued for at least 30 minutes after subcutaneous insulin
administration.
https\://app.geekymedics.com/osce-guides/prescribing/insulin-prescribing/ 3/511/13/24, 7\:43 PM Guide | Insulin prescribing

Prescribing considerations

Key points for safe insulin prescribing include\:
8
Prescribing by brand\: di
brand name to avoid errors.
Devices\: insulin is available in vials, pre-
devices and knows how to use them.
Write 'units' in full\: to avoid confusion (e.g. mistaking "
u
" for "0"), always write "
units" in full when prescribing insulin.
Insulin syringe\: all insulin doses should be measured and administered using an insulin syringe or commercial insulin pen
device. Intravenous syringes must never be used.
The Insulin Passport was launched by the National Patient Safety Agency (NPSA) in 2011 to minimise insulin-related errors. It
includes essential information about the patient's insulin type, delivery device, and emergency contacts. The NPSA
recommends that healthcare professionals review the passport each time insulin is prescribed, dispensed, or administered.

Side e

Typical side e
2
Hypoglycaemia\: the most common and serious side e
trained to recognise and manage hypoglycaemia.
Lipohypertrophy\: repeated injections at the same site can lead to fatty lumps, a
rotate their injection sites regularly.
Local injection site reactions\: redness, swelling, or discomfort at injection sites may occur. Injection technique should be
reviewed if reactions persist.
Cutaneous amyloidosis\: In 2020, the MHRA issued a warning about the risk of amyloid deposits forming under the skin at
injection sites. These deposits can interfere with insulin absorption, so injection sites should be checked regularly for lumps
or abnormalities.

Conclusion

Insulin therapy requires careful consideration of insulin types, patient needs, and special circumstances such as surgery.
Patients should be educated on adjusting insulin doses, rotating injection sites, and managing side e
Following current guidelines and tailoring therapy to individual needs can help achieve optimal glycaemic control while
minimising risks associated with insulin use.

References

1. Watts M. A n i m a l i n s u l i n . 2023. Available from\: [LINK]
2. BNF. I n s u l i n . 2024. Available from\: [LINK]
3. Diabetes UK. T y p e s o f i n s u l i n . 2022. Available from\: [LINK]
4. Patient.info. I n s u l i n R e g i m e n s . 2022. Available from\: [LINK]
5. NICE. C o n t i n u o u s s u b c u t a n e o u s i n s u l i n i n f u s i o n f o r t h e t r e a t m e n t o f d i a b e t e s m e l l i t u s . 2008. Available from\: [LINK]
6. BNF. D i a b e t e s , s u r g e r y a n d m e d i c a l i l l n e s s . 2024. Available from\: [LINK]
7. Dogra P, Anastasopoulou C, Jialal I. D i a b e t i c p e r i o p e r a t i v e m a n a g e m e n t . 2024. Available from\: [LINK]
8. NPSA. S a f e r a d m i n i s t r a t i o n o f i n s u l i n . 2010. Available from\: [LINK]
9. Birmingham and surrounds formulary. I n s u l i n G u i d e l i n e s f o r A d u l t s a n d C h i l d r e n w i t h T y p e 1 o r T y p e 2 D i a b e t e s M e l l i t u s . 2021.
Available from\: [LINK]

Reviewer

Anna Wozniak
Clinical Specialist Pharmacist
https\://app.geekymedics.com/osce-guides/prescribing/insulin-prescribing/ 4/511/13/24, 7\:43 PM Guide | Insulin prescribing
Source\: geekymedics.com
https\://app.geekymedics.com/osce-guides/prescribing/insulin-prescribing/ 5/5