Insulin therapy in primary care – key points for nurses

Continuing our series highlighting recent presentations from Nursing in Practice 365 events, diabetes nursing specialist Debbie Hicks shares key points on the management of insulin therapy for nurses in primary care

Insulin prescribing in the UK has tripled in the past decade, in particular due to an increase in use among those living with type 2 diabetes, now the largest group of insulin users.

As a result, nurses in general practice and the community are increasingly expected to be skilled in supporting people living with type 2 diabetes with insulin therapy and associated glucose monitoring.

The management of insulin therapy requires knowledge of the type of diabetes it is being used for and appropriate dosing, as well as correct injection technique, to prevent complications and medication errors.

Many people living with type 1 diabetes, and increasingly with type 2 diabetes taking insulin, now have access to continuous glucose monitoring (CGM) devices, with some also having insulin pumps, which are transforming lives for those on insulin and helping to reduce hypoglycaemic events.

Who needs insulin?

Type 1 diabetes

People with type 1 diabetes lack endogenous insulin due to an underlying autoimmune disorder. Anyone with type 1 diabetes will always need to take a combination of an intermediate – or long-acting insulin and a short-acting insulin via a pen device (unless they have one of the new insulin pumps).

Insulin therapy should never be stopped in a person with type 1 diabetes.

Type 2 diabetes

Many people with type 2 diabetes now use insulin; they may take it once or more times a day along with other diabetes treatments.

In type 2 diabetes the person may still produce some insulin, but due to insulin resistance they are experiencing hyperglycaemia to the extent they require insulin therapy, for example due to:

• Suboptimal glycaemic control on other glucose-lowering diabetes drugs.
• Infection/illness.
• Surgery or a fasted procedure.

Secondary or type 3c diabetes

This includes people with diabetes secondary to pancreatic damage or post-pancreatectomy.

Steroid induced diabetes

Some individuals treated with steroids for long periods develop steroid-induced diabetes and this can become unmanageable without insulin therapy.

Related Article: People with long-term conditions should have BMI check every year, says NICE

Gestational diabetes

Women who develop gestational diabetes during pregnancy and experience significant hyperglycaemia will need insulin therapy

Insulin therapy is error-prone

Unfortunately, insulin errors reportedly occur frequently – between 2003 and 2009 the National Reporting Learning System received 16,600 patient safety incidents involving insulin which included:

• 6 deaths
• 12 incidents involving severe harm due to insulin error
• Over 1,000 incidents causing moderate harm.

There are no more recent data from this, but the National Diabetes Audit reported in 2017 that insulin error occurred in 40% of people with type 1 diabetes and 37% in those with type 2 diabetes.

Making sure insulin is administered correctly is key to mitigating the risk of errors; while the above raises questions regarding the documenting of errors, it is vital that nurses report any errors in insulin administration to ensure appropriate review of systems and education to help prevent future errors.

Types of insulin and their management

There are around 30 different insulin preparations. Many preparations have similar names but differ in their mode of action; the naming is a common cause of errors in insulin prescribing and administration which can lead to harm.

Animal insulin products are rarely used now; human and analogue insulin products are the most commonly prescribed, with ‘biosimilar’ insulin also now available in the UK.

Most insulin is prescribed as 100 units per mL (U100); other concentrations are now available including 200 units per mL (U200) and 300 units per mL (U300).

Insulin therapy is given in a variety of regimens according to clinical need and individuals’ preferences (see box).

Ensuring good injection technique

For any insulin preparation to act as it should it is vital that it is administered into the subcutaneous tissue correctly. The correct injection technique is crucial to achieve the expected absorption and action of insulin.

All children and many adults with type 1 diabetes also now have automatic insulin pumps linked to a CGM device so they don’t need to inject their insulin.

Related Article: Gestational diabetes management – what nurses in primary care need to know

However, most people are still injecting insulin and it is vital for nurses in primary care to be familiar with the different insulin injection devices. These include: insulin vials and syringes (though rarely used now); re-useable insulin pens with insulin cartridges; and disposable prefilled pens.

A major complication of poor injection technique that can prevent the appropriate uptake of insulin, is lipohypertrophy; a ‘lipo’ is a lump or swelling that develops in the subcutaneous tissue due to injecting repeatedly into the same site. It can be avoided by rotating the injection site, using a new needle for each injection and checking injection sites regularly.

One study showed that an education programme improved the proportion of people with diabetes using the correct technique from 15% prior to the education to over 80% after. In addition, overall glycaemic control improved (mean HbA1c reduction of 0.4%, or 4 mmol/L), while the average number of insulin units required was reduced by 6 units per person per day and lipohypertrophic lesions were reduced by 50%. In addition, unexplained hypoglycaemic events reduced by 40% and glycaemic variation reduced by 42%.

The following factors are vital for good injection technique:

• Correct needle length
  • Insulin must be injected into the subcutaneous fat layer, for predictable and stable absorption; intramuscular deposition leads to accelerated absorption and an increased risk of hypoglycaemia
  • Longest needle requirement is 4mm – skin thickness does not vary much with, eg, age, gender or ethnicity, and is not affected by someone’s weight.
• Correct re-suspension of insulin.
• Correct injection sites
  • Best sites for injecting insulin include: back of the upper arms (difficult when self-injecting); the abdomen; upper outer area of buttocks; upper outer area of thighs
  • Always check the site chosen for lipohypertrophy or bruising before injecting.
• Correct rotation technique
  • Important not to overuse same injection site as this can cause problems like lipohypertrophy
  • Advise patients to rotate within the chosen site – eg, divide abdomen into four quadrants and change quadrant on weekly basis; also make sure each injection given 1cm away from the last.
• Single use of needles
  • All people with diabetes who are self administering insulin should be given a sharps box; some areas provide this as a free delivery / collection service.
• Correct angle of injection to ensure subcutaneous fat deposition is 90 degrees to the skin. The use of lifted skin fold should be used eg, for children and lean individuals.
• Regular examination and palpation of injection sites by person with diabetes and HCP to detect lipohypertrophy.

If you are required to administer insulin injections to a person with diabetes remember the following:

• You must be familiar with the device and competent to use it.
• Never draw up insulin from a pre-filled or cartridge pen using a syringe.
• When using an insulin pen use the correct pen device aligned to the insulin make
• Use a new needle each time.
• You must use a safety needle to administer a third-party injection to avoid needlestick injury. This became UK law in 2013.
• Always make sure there is enough insulin in the pen before injecting; if not use a new pen – do not try to part-dose.
• Do not withdraw the pen needle before all the insulin has been administered.

Avoiding dosing errors

The correct dose is closely tailored to the clinical needs of the individual and so sensitive to error.

One simple but potentially catastrophic error is for the ‘U’ to be misread as a ‘0’ or other number, leading to 10 x the dose being given – so, eg, ‘42U’ being taken to be ‘420’.

More subtle but important mistakes can happen if there are issues affecting glucose levels – including diet and activity levels – requiring changes in the appropriate dose/regimen, or with the timing of dosing or the injection technique.

Timing of insulin administration is key. A common reason for mistiming in the community setting is where older people are being given injections by community nursing staff who cannot visit every person at an appropriate time patients to fit in with a care home’s schedule, leading to, for example, insulin being given too early before or being given after a meal. Initiatives to train more staff including healthcare assistants in insulin administration may alleviate this issue.

Key points to remember include:

• Check CGM profiles (if available) closely or ensure regular HbA1c monitoring every 3 months to inform decisions on insulin dosing and timing.
• Before changing doses, check injection sites in case there is an issue that might affect insulin uptake such as lipohypertrophy.
• When switching from a poor to a healthy injection site, there is a high risk of hypoglycemia, so the insulin dose should be reduced by at least 10%.
• When switching people from one insulin regimen to another, the dose of the new form of insulin will usually be reduced – it is vital to check the individual Summary of Product Characteristics for this.
• Ensure that the ‘U’ for dosing unit is not misunderstood as the dose.

Summary points for primary care

• Always review the injection technique and injection sites for people with diabetes under your care.
• Ensure healthcare workers administering insulin understand the correct injection technique and have access to safety needles.
• Understand situations requiring dose adjustments and the principles of insulin adjustment; for example: reducing insulin doses by at least 10% when people switch to a healthier injection site to avoid hypoglycemia.
• Use glucose profiling to inform decisions on insulin therapy.
• Ensure regular monitoring and adjustments based on physical activity and other factors.

Debbie Hicks has worked in diabetes nursing for over 34 years as diabetes specialist nurse, nurse consultant and diabetes lead at Medicus Health Partners, North London. She is the director of Trend Diabetes.

Sources and further reading

Frid A, Lind B. Intraregional differences in the absorption of unmodified insulin from the abdominal wall. Diabetic Med 1992; 9:236-239

Related Article: Tool predicts most effective glucose-lowering drugs for type 2 diabetes patients

Vaag A, Damgaard Pedersen K, Lauritzen M et al. Intramuscular versus subcutaneous injection of unmodified insulin: consequences for blood glucose control in patients with type 1 diabetes mellitus. Diabet Med 1990; 7(4):335-42

Smith M, Clapham L, Strauss K. UK Lipohypertrophy Interventional Study 2017. Diabetes Res Clinical Pract 2017;126:248-253

For more information visit the Trend Diabetes website: Trend Diabetes – The heartbeat of diabetes nursing

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