Karen Bartha discusses recommendations for the safe prescribing of insulin and the types of insulin available for different patient groups.

Blackwood karen

After reading this article, ‘Test and reflect’ on your updated knowledge with our multiple-choice questions. Earn 0.5 CPD credits for reading this article and an additional 0.5 CPD credits for completing the MCQs.

There are approximately 4.5 million people with diabetes in the UK, 10% of these people will have type 1 diabetes, where insulin is essential for life; the remaining 90%, have type 2 diabetes—many of these people will progress to require insulin.1,2 Treatment with insulin can improve the quality of life for many individuals; however, errors in insulin prescribing and management are very common and can lead to patient harm.3 With such high levels of patients using insulin, and the continuing shift of responsibility into primary care for routine diabetes care,4 it is imperative that healthcare professionals (HCPs) increase their knowledge and understanding of insulin. Insulin therapy, for people with type 2 diabetes, should only be initiated and managed by HCPs with the relevant expertise and training.5

A free e-learning module The six steps to insulin safety,6 developed by the Primary Care Diabetes Society in association with Training, Research and Education for Nurses in Diabetes (TREND) UK, is available for all those prescribing, managing, or administering insulin, with the overall aim of reducing errors in clinical practice.7 The Royal College of Nursing (RCN) recommend completion of such e-learning modules, and utilisation of local training and support; referring to ‘An integrated career and competency framework for diabetes nursing’ for the competencies required for the safe administration and use of insulin.4,8 Once you have read this article, multiple-choice questions are available to test and reflect on your learning.

This article will consider what information is required by individuals taking insulin to increase their safety; and the knowledge and skills required by those HCPs who prescribe insulin or are involved in the ongoing management of individuals on insulin.

NICE have released a key therapeutic topic focussing on safety issues with insulin:7

1) Hypoglycaemia

Hypoglycaemia is an inevitable adverse effect of insulin therapy. It can range from mild, which includes symptoms such as hunger, anxiety or irritability, palpitations, sweating, or tingling lips, to severe which can result in convulsions, loss of consciousness, and coma.

All the NICE guidelines on diabetes recommend that people receiving insulin therapy are provided with education and information about awareness and management of hypoglycaemia.7

Hypoglycaemia cannot always be explained, but is more likely to occur due to a missed or late meal, excess insulin or not enough carbohydrate ingested, unplanned physical activity, or as a consequence of alcohol.9 Recommended initial treatment of hypoglycaemia is with 15–20 g of rapid-acting carbohydrate, such as 150 ml (a small can) of non-diet fizzy drink, 5–6 dextrose tablets, or 200 ml (a small carton) of smooth orange juice.10 Additional information regarding hypoglycaemia in adults for healthcare professionals is available from TREND UK.11  The updated patient information leaflet on the recognition and management of hypoglycaemia is also available from TREND UK.12

2) Driving

People with diabetes who are using insulin therapy must notify the Driver and Vehicle Licensing Agency (DVLA). The presence of certain diabetes complications such as visual and renal complications may mean that a person needs to stop driving and notify the DVLA depending on the circumstances. People with impaired awareness of hypoglycaemia must not drive and must notify the DVLA.7

For Group 1 drivers (car and motorcycle), blood glucose testing needs to be done no longer than 2 hours before driving, and every 2 hours while driving on a long journey;13 it should be above 5 mmol/l to drive and driving should not be performed until 45 minutes after the management of a hypoglycaemic episode.3 Applicants will be asked to sign an undertaking to comply with the directions of the HCPs managing their diabetes.13

More information for HCPs, including information relating to Group 2 drivers, is available in the DVLA guide Assessing fitness to drive—a guide for medical professionals.13 Patient information leaflets are available from both the DVLA and TREND UK.13,14

3) ‘Sick-day’ rules

The NICE guidelines on type 1 and 2 diabetes in children and young people, and type 1 diabetes in adults recommend that clear guidance (‘sick day rules’) should be given to all people with type 1 diabetes (and their family or carers where appropriate) to help them to manage their condition appropriately during periods of illness.7 This should include:15

  • not stop their insulin therapy; the dose of insulin may need to be altered during periods of illness
  • monitor their blood glucose levels more frequently; the insulin dose should be titrated according to the blood glucose results
  • monitor their ketone levels, they should contact the GP or diabetes team immediately if ketones are high (that is, above 2+ in the urine or above 3 mmol/l in the blood)
  • maintain their normal meal pattern (where possible) if appetite is reduced, their normal meals could be replaced with carbohydrate-containing drinks (such as milk, milk shakes, fruit juices, and sugary drinks)
  • maintain adequate fluid intake to prevent dehydration; if vomiting or diarrhoea is persistent, they should seek immediate medical advice as intravenous fluids may be required
  • seek urgent medical advice if they are violently sick, drowsy, or unable to keep fluids down
  • when feeling better, continue to monitor their blood glucose carefully until it returns to normal.

Further information for HCPs, regarding the management of intercurrent illness is available from TREND UK16 and for patients, advice regarding ‘sick-day’ rules are available from Diabetes UK.17 Specific advice regarding ‘sick-day’ rules for Type 1 diabetes and for Type 2 diabetes are available from TREND UK.18,19 

4) Continuous subcutaneous insulin infusion (insulin pump) therapy

Individual medical device alerts should be referred to.7

5) Insulin prescribing and administration: reducing errors

Several new insulin products have been launched recently,7 and various reports have been released to improve safety and reduce errors.

The European Medicines Agency recognise the increased potential for error with high strength insulins and recommend that: patients are provided with adequate information about their insulin; that insulin should always be prescribed as units (the word ‘units’ to be spelled out in lower case); that patients should monitor their glucose more regularly when changed to high strength insulin; and the key message, which was stressed by NHS improvement, that a needle and syringe should never be used to withdraw insulin from a pre-filled pen device or cartridge.20,21

The Medicines and Healthcare products Regulatory Agency reinforce the National Patient Safety Agency recommendation that patients be provided with an information booklet and insulin passport (or safety card).22,23 NHS improvement in conjunction with TREND UK have since produced Keeping safe with insulin therapy for patients, which focuses on these key areas:3

  • the right person
  • the right insulin
  • the right dose
  • the right time
  • the right device
  • the right way.

Available insulin products

In the UK, three types of insulin are available:5

  • human insulins are produced by recombinant DNA technology and have the same amino acid sequence as endogenous human insulin
  • human insulin analogues are produced in the same way as human insulins, but the insulin is modified to produce a specific desired kinetic characteristic (such as an extended duration of action or faster absorption and action)
  • animal insulins are extracted and purified from animal sources, either cows (bovine insulin) or pigs (porcine insulin)—since these insulins are rarely used they will not be covered further.

Table 1: available insulin products in the UK24

 Time-action profileGeneric name (brand name)*Commonly-used compatible pen deviceComments

Intermediate-acting (isophane or NPH) insulins:



Onset of action of approximately 1–2 hours, maximal effects between 4–12 hours, and a duration of action of 16–35 hours5,15


Insulin human (Humulin® I) 100 IU/ml




3 ml cartridge with HumaPen®

The shorter duration of action, can prove useful when used once daily in a morning, potentially reducing overnight drop in blood glucose

Insulin human (Insuman basal®) 100 IU/ml




3 ml cartridge with ClikSTAR® or AllStar™


Insulin human (Insulatard®) 100 IU/ml


3 ml PenFill with NovoPen® 5

Long-acting insulin analogues:



Used once daily and achieve a steady-state level after 2–4 days to produce a constant level of insulin. Mimic basal insulin but can last for a longer period than intermediate-acting insulins5,15




Insulin detemir (Levemir®) 100 units/ml

(Once or twice daily)


3 ml PenFill with NovoPen® 5 or InnoLet®

As an alternative to intermediate-acting insulin in type 2 diabetes


Insulin glargine (Lantus®) 100 units/ml



3 ml cartridge with ClikSTAR® or AllStar™


Insulin glargine (Abasaglar®▼) 100 units/ml


3 ml Cartridge with HumaPen®

Biosimilar insulin glargine; consider prescribing by brand to ensure correct preparation is received


Insulin glargine (Semglee®▼) 100 units/ml

Only available as 3 ml pre-filled pen

Ultra-long-acting insulins:


Once daily basal insulin, achieving steady state after 2-3 days, duration of action above 42 hours24

Insulin degludec (Tresiba®) 100 units/ml

FlexTouch, 3 ml cartridge with NovoPen 5

May prove useful if regular timing of basal insulin is difficult

Rapid-acting insulin analogues:



Onset of action within 15 minutes and duration of action of 2–5 hours; consequently, they can be injected 5–15 minutes before meals, with meals, or soon after meals5,15

Insulin aspart (Novorapid®) 100 units/ml

FlexPen®, FlexTouch®,

3 ml PenFill with NovoPen 5®

Dose can be adjusted dependent on dietary intake and blood glucose, with the appropriate education

Insulin lispro (Humalog®) 100 units/ml


3 ml cartridge with HumaPen®

Insulin glulisine (Apidra®) 100 units/ml


3 ml cartridge with ClikSTAR® or AllStar™


Fast-acting insulin aspart

Onset of action within 10 minutes, maximum lowering effect at 1-3 hours, with a duration of action of 3-5 hours24

Insulin aspart (Fiasp®▼) 100 units/ml


3 ml PenFill with NovoPen 5®

May improve post prandial glucose control21

Short-acting soluble insulins:


Generally injected 30 minutes before food and have an onset of action of 30–60 minutes and a duration of action of up to 8 hours5,15






Insulin human (Actrapid®) 100 IU/ml




10ml Vial

No longer commonly used, but some patients will still be on them. Should be administered with food, caution with stacking of insulin due to duration of action

Insulin human (Humulin® S) 100 IU/ml

3 ml cartridge with HumaPen®, or 10 vial


Insulin human (Insuman® Rapid) 100 units/ml

3ml cartridge with ClikSTAR®

Bi-phasic (mixed) insulins:






A combination of rapid-acting analogue and intermediate-acting insulin



Insulin aspart/ protamine-crystallised insulin aspart (Novomix® 30) 100 units/ml



3 ml PenFill with NovoPen® 5

Must be administered with meals, better suited to those with regular mealtimes

Insulin lispro /insulin lispro protamine (Humalog® Mix25) 100 units/ml



3 ml cartridge with HumaPen®

Insulin lispro /insulin lispro protamine (Humalog® Mix50) 100 units/ml


3 ml cartridge with HumaPen®

A combination of short-acting soluble insulin and intermediate-acting insulin



Insulin human/crystalline protamine insulin human (Insuman® Comb 25) 100 IU/ml

3ml cartridge with ClikSTAR®


Insulin human/crystalline protamine insulin human (Insuman® Comb 50) 100 IU/ml


3 ml cartridge with ClikSTAR® or AllStar™


Soluble insulin human/isophane insulin human (Humulin® M3) 100 IU/ml


3 ml cartridge with HumaPen®

High strength insulins:

Once daily basal insulin, achieving steady state after 2-3 days, duration of action above 42 hours24

Insulin degludec (Tresiba®) 200 units/ml


Consider using higher strength insulin for patients taking large doses, to reduce volume25

Once daily basal insulin, duration of action above 24 hours24

Insulin glargine (Toujeo®) 300 units/ ml



Rapid-acting mealtime insulin (profile as other rapid-acting analogues)

Insulin lispro (Humalog®) 200 units/ml


3 ml cartridge with HumaPen®

NPH=neutral protamine Hagedorn; IU=international units

*See BNF for a full list of current medications and devices available; the list of devices included here may not be comprehensive.

NICE recommendations on insulin

NICE recommend use of twice‑daily insulin detemir (Levemir) as basal insulin therapy for adults with type 1 diabetes, with a rapid-acting insulin analogue injected before meals, as part of a multiple daily injection basal–bolus insulin regimen. Consider once-daily insulin glargine or insulin detemir if twice‑daily basal insulin injection is not acceptable to the person, or once‑daily insulin glargine if insulin detemir is not tolerated.26

In type 2 diabetes, the decision to initiate insulin will usually be driven by; deteriorating glycaemic control, symptomatic hyperglycaemia, persistently elevated HbA1c in spite of adjustments to or maximisation of oral hypoglycaemic agents (OHAs), intolerance to OHAs, personal preference, pregnancy or planning pregnancy, or during acute illness or treatment with steroid therapy.4

NICE recommend; if an adult with type 2 diabetes is symptomatically hyperglycaemic, consider insulin.27  When starting insulin therapy in adults with type 2 diabetes, continue to offer metformin for people without contraindications or intolerance. Review the continued need for other blood glucose lowering therapies.27 When starting insulin in type 2 diabetes NICE suggest choosing from a number of insulin types and regimens:27

  • offer neutral protamine Hagedorn (NPH) insulin injected once or twice daily according to need
  • consider starting both NPH and short‑acting insulin (particularly if the person’s HbA1c is 75 mmol/mol [9.0%] or higher), administered either:
    • separately or
    • as a pre-mixed (biphasic) human insulin preparation
  • consider, as an alternative to NPH insulin, using insulin detemir or insulin glargine if:
    • the person needs assistance from a carer or HCP to inject insulin, and use of insulin detemir or insulin glargine would reduce the frequency of injections from twice to once daily or
    • the person’s lifestyle is restricted by recurrent symptomatic hypoglycaemic episodes or
    • the person would otherwise need twice‑daily NPH insulin injections in combination with oral glucose‑lowering drugs
  • consider pre-mixed (biphasic) preparations that include short‑acting insulin analogues, rather than pre‑mixed (biphasic) preparations that include short‑acting human insulin preparations, if:
    • a person prefers injecting insulin immediately before a meal or
    • hypoglycaemia is a problem or
    • blood glucose levels rise markedly after meals.

Consider switching to insulin detemir or insulin glargine from NPH insulin in adults with type 2 diabetes:27

  • who do not reach their target HbA1c because of significant hypoglycaemia or
  • who experience significant hypoglycaemia on NPH insulin irrespective of the level of HbA1c reached or
  • who cannot use the device needed to inject NPH insulin but who could administer their own insulin safely and accurately if a switch to one of the long‑acting insulin analogues was made or
  • who need help from a carer or HCP to administer insulin injections and for whom switching to one of the long‑acting insulin analogues would reduce the number of daily injections.

Monitor adults with type 2 diabetes who are on a basal insulin regimen (NPH insulin, insulin detemir, or insulin glargine) for the need for short‑acting insulin before meals (or a pre‑mixed [biphasic] insulin preparation).27

Monitor adults with type 2 diabetes who are on pre‑mixed (biphasic) insulin for the need for a further injection of short‑acting insulin before meals or for a change to a basal bolus regimen with NPH insulin or insulin detemir or insulin glargine, if blood glucose control remains inadequate.27

Injection technique

Evidence-based recommendations for best practice when using injectable therapies in diabetes, for both HCPs and people with diabetes, are included in The UK Injection and Infusion Technique Recommendations 4th edition developed by The Forum for Injection Technique (FIT) UK.25 Health outcomes for people with diabetes can be improved through delivery of the correct dose, to appropriate injection site using the correct technique.25  An additional resource is available for HCPs: ‘Best practice guideline to support Correct Injection Technique in Diabetes Care’28

Closing thoughts

In type 2 diabetes, if insulin is initiated in a timely manner in deteriorating glycaemic control (HbA1c above 58mmol/mol) an intermediate-acting NPH insulin or long-acting basal analogue insulin may be appropriate as first choice, with NPH insulin offering the most cost-effective treatment option.27 While NICE recommend consideration of a short-acting soluble insulin, in conjunction to NPH insulin,27 in those patients with HbA1c greater than 75 mmol/mol, the longer duration of action of short-acting insulin (up to 8 hours) compared with that for rapid-acting insulin (up to 5 hours) should be considered due to the risk of stacking insulin. Consideration should also be given to the time of onset of action—patients will need to inject 30 minutes prior to eating with short-acting soluble insulin versus 5–15 minutes before meals, for rapid-acting insulin analogues. While metformin should be continued, if tolerated or not contraindicated, the ongoing need for other OHAs should be reviewed. Glycaemic control will require ongoing review and reassessment of the current insulin regimen, plus adequate and ongoing titration of insulin doses. If insulin adjustment is required, it should only be done by HCPs with the relevant expertise and training.5

Further information on insulin dose titration can be sought from:

When starting insulin therapy in adults with type 2 diabetes, use a structured programme employing active insulin dose titration that encompasses:27

  • injection technique, including rotating injection sites and avoiding repeated injections at the same point within sites
  • continuing telephone support
  • self-monitoring
  • dose titration to target levels
  • dietary understanding
  • DVLA guidance
  • management of hypoglycaemia
  • management of acute changes in plasma glucose control
  • support from an appropriately trained and experienced healthcare professional.

With the growing numbers of patients on insulin, and the recognised concerns around the safe use of insulin, it is essential that HCPs work within their professional scope of practice. HCPs must increase their knowledge and understanding of available insulin products through utilisation of the resources available to them, such as the e-learning modules identified and any local training opportunities. In addition, the provision of patient information materials increases patient knowledge and in turn safety.

Now Test and reflect: view our multiple choice questions


  1. Diabetes UK. Facts and stats. Diabetes UK, 2016. Available at: diabetes-resources-production.s3-eu-west-1.amazonaws.com/diabetes-storage/migration/pdf/DiabetesUK_Facts_Stats_Oct16.pdf
  2. American Diabetes Association. 8. Pharmacological approaches to glycemic treatment. Diabetes Care 2017; 40 (Suppl 1): 64–74.
  3. Training, Research and Education for Nurses in Diabetes (TREND) UK. Keeping safe with insulin therapy. TREND UK, 2017. Available at: trend-uk.org/wp-content/uploads/2017/05/A5_Insulin_TREND_FINAL.pdf
  4. Royal College of Nursing (RCN). Starting injectable treatment in adults with type 2 diabetes. RCN, 2012. Available at: www.rcn.org.uk/-/media/royal-college-of-nursing/documents/publications/2013/may/pub-002254.pdf
  5. NICE. Insulin therapy in type 2 diabetes. NICE Clinical Knowledge Summaries. NICE, 2016. Available at: cks.nice.org.uk/insulin-therapy-in-type-2-diabetes
  6. Diabetes on the Net CPD Centre. The six steps to insulin safety. SB Communications Ltd, 2017. www.diabetesonthenet.com/course/the-six-steps-to-insulin-safety/details (accessed 22 March 2019).
  7. NICE. Safer insulin prescribing. NICE Key Therapeutic Topic 20. Available at: www.nice.org.uk/advice/ktt20/chapter/Evidence-context (accessed 22 March 2019).
  8. Training, Research and Education for Nurses in Diabetes (TREND) UK. An integrated career and competency framework for diabetes nursing—4th edition. Available at: trend-uk.org/wp-content/uploads/2017/02/TREND_4th-edn-V10.pdf
  9. Diabetes UK. What is a hypo? www.diabetes.org.uk/Guide-to-diabetes/Complications/Hypos (accessed 22 March 2019).
  10. Diabetes UK. Having a hypo. www.diabetes.org.uk/Guide-to-diabetes/Complications/Hypos/Having-a-hypo/ (accessed 22 March 2019).
  11. Training, Research and Education for Nurses in Diabetes (TREND) UK. Hypoglycaemia in adults in the community: recognition, management and prevention. Trend UK, 2018. Available at: trend-uk.org/wp-content/uploads/2018/09/HCP_Hypo_TREND_FINAL.pdf
  12. Training, Research and Education for Nurses in Diabetes (TREND) UK. Diabetes:why do I sometimes feel shaky, dizzy and sweaty? Trend UK, 2017. Available at: trend-uk.org/wp-content/uploads/2018/03/A5_6pp_Hypo_TREND_CONNECT.pdf
  13. Driver and Vehicle Licensing Agency (DVLA). Assessing fitness to drive—a guide for medical professionals. DVLA, 2017. Available at: assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/783444/assessing-fitness-to-drive-a-guide-for-medical-professionals.pdf
  14. Training, Research and Education for Nurses in Diabetes (TREND) UK. Diabetes: safe driving and the DVLA. Trend UK, 2016. Available at: trend-uk.org/wp-content/uploads/2018/03/A5_6pp_Driving_TREND_CONNECT.pdf
  15. NICE. Insulin therapy in type 1 diabetes. NICE Clinical Knowledge Summaries. NICE, 2016. Available at: cks.nice.org.uk/insulin-therapy-in-type-1-diabetes
  16. Training, Research and Education for Nurses in Diabetes (TREND) UK. Resources. Trend UK. Available at: trend-uk.org/resources (accessed 22 March 2019)
  17. Diabetes UK. Dealing with illness. www.diabetes.org.uk/Guide-to-diabetes/Life-with-diabetes/Illness/ (accessed 22 March 2019).
  18. Training, Research and Education for Nurses in Diabetes (TREND) UK.Type 1 diabetes: what to do when you are ill. Trend UK, 2018. Available at: trend-uk.org/wp-content/uploads/2018/03/A5_T1Illness_TREND_FINAL.pdf
  19. Training, Research and Education for Nurses in Diabetes (TREND) UK. Type 2 diabetes: what to do when you are ill. Trend UK, 2018. Available at: trend-uk.org/wp-content/uploads/2018/12/A5_T2Illness_TREND.pdf
  20. European Medicines Agency (EMA). Guidance on prevention of medication errors with high-strength insulins. EMA, 2015. Available at: www.ema.europa.eu/docs/en_GB/document_library/Recommendation_on_medication_errors/2015/11/WC500197133.pdf
  21. NHS improvement. Patient safety alert—risk of severe harm and death due to withdrawing insulin from pen devices. NHS Improvement, 2016. Available at: improvement.nhs.uk/documents/510/Patient_Safety_Alert_-_Withdrawing_insulin_from_pen_devices.pdf
  22. Medicines and Healthcare products Regulatory Agency (MHRA). High strength, fixed combination and biosimilar insulin products: minimising the risk of medication error. www.gov.uk/drug-safety-update/high-strength-fixed-combination-and-biosimilar-insulin-products-minimising-the-risk-of-medication-error (accessed 22 March 2019)
  23. National Patient Safety Agency (NPSA). Patient safety alert—the adult patient’s passport to safer use of insulin. NPSA, 2011. Available at: www.sps.nhs.uk/wp-content/uploads/2018/02/2011-NRLS-1283-Supporting-infoinsulin-FINAL-110812.pdf
  24. Datapharm Ltd. Electronic medicines compendium. www.medicines.org.uk/emc/ (accessed 22 March 2019)
  25. Forum for Injection Technique (FIT) UK. The UK Injection and Infusion Technique Recommendations 4th edition. FIT UK, 2016. Available at: fit4diabetes.com/files/4514/7946/3482/FIT_UK_Recommendations_4th_Edition.pdf
  26. NICE. Type 1 diabetes in adults: diagnosis and management. NICE Guideline 17. NICE, 2016. Available at: www.nice.org.uk/guidance/ng17
  27. NICE. Type 2 diabetes in adults: management. NICE Guideline 28. NICE, 2017. Available at: www.nice.org.uk/guidance/ng28
  28. Training, Research and Education for Nurses in Diabetes (TREND) UK. Best Practice Guideline to support Correct Injection Technique in Diabetes Care. Trend UK, 2018. Available at: trend-uk.org/wp-content/uploads/2018/11/ITM-Guideline_v9-FINAL-251018.pdf
  29. Oxfordshire Clinical Commissioning Group: Insulin Initiation and Adjustment in Type 2 Diabetes Primary Care Guideline. Available at: clinox.info/clinical-support/local-pathways-and-guidelines/Clinical%20Guidelines/Insulin%20Initiation%20and%20Adjustment%20in%20Type%202%20Diabetes.pdf