GGC Medicines

Adult Therapeutics Handbook

Types of Antidiabetic Drugs

Types of Antidiabetic Drugs

Injectable therapies


For all patients starting insulin for the first time please contact a diabetic nurse specialist (most patients are started on twice daily mixed insulin). When prescribing insulin please specify the type and dose on both the drug kardex and insulin prescription chart.

The following are some of the insulins available. If you are unsure of the type of insulin the patient is on, contact either your clinical pharmacist to help clarify or your local Diabetes Team for guidance.

Short-acting insulin

Humalog® (insulin lispro)

NovoRapid® (insulin aspart)

Humulin S®


Intermediate- and Long-acting insulin (basal)

Humulin I®


Lantus® (insulin glargine)

Levemir® (insulin detemir)

Abasaglar® (biosimilar insulin glargine)

Tresiba® U100 (insulin degludec)

Tresiba® U200 (concentrated insulin degludec, 200units/ml)

Toujeo® U300 (concentrated insulin glargine, 300units/ml)

Mixture of short- and intermediate-acting: Mixed insulin

Humulin M3®

Humalog® Mix25

Humalog® Mix50

Novomix® 30

The list above reflects the majority of types of insulin used locally. For a complete reference of all insulins, refer to BNF.

N.B. Do not give hyperglycaemic patients boluses of SC insulin on an 'as required' basis, adjust their regular therapy instead. Check urine or capillary blood for ketones. If ketones found then follow local guidelines, which may necessitate starting Variable Rate Intravenous Insulin Infusion.

Insulin prescribing - Important points

Insulin is an important medication that when prescribed poorly can lead to severe complications and even mortality. Below are four key components to safer insulin prescribing:

  1. The right insulin - ensure that the correct insulin is prescribed in full in both the Kardex and the insulin prescription chart. Check with the patient and the GP if necessary.

    Note: Remember - the "25" in Humalog Mix 25 and the "30" in Novomix 30 refers to the percentage of rapid acting insulin in the mix, not the dose.

  2. The right time - prescribe insulin at the right time to reduce risk of hypoglycaemia

    Example: Short-acting insulin should be prescribed before meals (can be written before breakfast, before lunch, before dinner). Premixed twice daily insulin such as Novomix 30 is generally prescribed before breakfast and evening meal.

    If possible, prescribe evening dose of long-acting insulin earlier in the day and morning dose of insulin the day before. Use the previous day's results to guide you. If you cannot prescribe next morning insulin dose, tell the night shift to ensure insulin is given with breakfast where appropriate.

  3. The right dose - confirm insulin dose with two sources as per Medicines Reconciliation Policy (see guideline on Good Prescribing Practice - General Advice). Do not use abbreviations such as IU or U - write "units" in full where indicated.

    Note: Remember U200 and U300 pen devices contain concentrated insulin which should always be administered by the pen device. Never use an insulin syringe to draw up insulin from these pens or there will be a significant risk of insulin overdose.

  4. The right way - only use an insulin syringe to draw up insulin. Never use a normal syringe.

Advice on managing inpatients using insulin pumps (or CSII, continuous subcutaneous insulin infusion)

Patients on an insulin pump have Type 1 Diabetes and are well trained in managing their diabetes and their pump. Insulin pumps infuse short-acting insulin only, so if the infusion is stopped for any reason the patient can rapidly descend into diabetic ketoacidosis (DKA). During any period the patient is unable to self manage the pump e.g. comatose, acutely unwell, the pump should be removed and replaced with either intravenous insulin or multiple subcutaneous insulin injections as directed.

Pump management

  • Patients using pump therapy have a continuous supply of background insulin and therefore do not have to eat at set times. Fasting is not a problem for pump users.
  • Patients usually treat mild hypoglycaemia by taking 15g – 20g dextrose or fast acting carbohydrate (e.g. Dextrosol® 5 - 7 tablets or Glucotabs® 4 - 5 tablets or Original Lucozade® 170ml or Pure fruit juice 150 - 200ml)
  • Test blood glucose level after 10 - 15 minutes. Turning off the pump is not usually required.
  • If the patient is admitted unconscious, do not cut tubing. Remove catheter from abdomen and place pump in a safe place.
  • Patients admitted to hospital (including those with hypo and hyperglycaemia) should continue to manage their diabetes using their pump.

Patients will require an alternative insulin regime immediately if:

  • Unconscious
  • Illness prevents self-management
  • Undergoing major surgery
  • Have DKA

For anymore information please contact the local Diabetes Team.


If a patient on a pump is admitted with DKA and they are conscious and able to manage the pump then continue with the basal rate programmed into the pump but manage them according to the DKA guideline. Once the patient is well enough to eat and drink they can restart the boluses via the pump.

If a patient on a pump is admitted with DKA and is unconscious or unable to manage their pump then it should be removed and stored safely and the patient should be treated as per the DKA guideline.


In the unusual event of a patient being admitted with hypoglycaemia and is unconscious, treat as per the Hypoglycaemia guideline, and stop / remove the pump. If the patient regains consciousness and is able to self manage, the pump should be restarted by the patient. If the patient is unable to restart the pump, basal SC insulin should be given.

Glucagon-like peptide 1 (GLP-1) agonists

Only initiate on specialist advice. This class includes:

  • Exenatide (Byetta®)
  • Liraglutide (Victoza®)
  • Lixisenatide (Lyxumia®)
  • Exenatide LAR (Bydureon®) weekly dosing
  • Dulaglutide (Trulicity®) weekly dosing

See BNF for dosing details and contraindications. See GGC Formulary for restrictions on use.

Oral antidiabetic drugs

Below is a list of the different types of oral antidiabetic agents. Contact the Diabetes Team if in doubt when prescribing these agents and if further advice is needed.


  • Metformin 500mg with breakfast for 1 week, then 500mg with breakfast and evening meal for at least 1 week, then 500mg with breakfast, lunch and evening meal (maximum dose is 2g in divided doses). N.B. Avoid metformin if eGFR <30ml/minute/1.73m2. Dose reduce if eGFR 30-45ml/minute/1.73m2.

Patients can experience some gastrointestinal upset with metformin. By starting at a low dose with food this is less likely. Normally these symptoms will resolve so it is worthwhile advising patients to persevere with it. Contact the Diabetes Team if in doubt and if further advice is needed.


  • Gliclazide: initially 40–80mg daily, at mealtime, adjusted according to response. Maximum 320mg daily. Alternative to gliclazide is glipizide (see BNF for details).


Only initiate on specialist advice. Follow BNF instructions regarding monitoring LFTs after initiation of therapy.

  • Pioglitazone initially 15–30mg once daily increased to 45mg daily according to response.

Dipeptidyl peptidase IV inhibitors

Only initiate on specialist advice. See GGC Formulary ( for specific restrictions. The preferred agents in the formulary are alogliptin and linagliptin.

Sodium-glucose co-transporter 2 inhibitor

Only initiate on specialist advice. See BNF for dosing details and contraindications. See GGC Formulary for restrictions on use. This class includes:

  • Dapagliflozin
  • Canagloflozin
  • Empagliflozin


Content last updated June 2019