Insulin Therapy

Uses of Insulin

• Insulin is the mainstay of treatment in Type 1 DM due to the absolute deficiency of insulin
  • Also needed in late-stage T2DM

• Useful in chronic glycaemic control (maintain Hba1c ≤ 6.5%) but also in the management of acute complications (DKA/HHS)

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Dosing insulin

• • • 1 unit of insulin usually brings glucose down by 2-3mmol
      • Regardless of insulin type
      • However, this does vary by patients

• • • Dosing insulin is based on weight but depends on the patient
      •  Start with around 0.5unit/kg 

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Types of Insulin

• • • Mainly categorised according to duration –
      • Insulin can be rapid, short, medium, or long acting and different types are used

• • • Rapid – Lasts for <6 hours and is typically used before/after meals
      • These are analogue insulins
      • Peaks at 30-120 mins
      • Lispro (Humalog), Aspart (novorapid?), glulisine

• • • Short-acting insulins
      • I.e. soluble insulins
      • Take 30 mins to act, peak at 4 hours
      • Less commonly used now in maintenance
        • But are the only option for IV use (FRII/VRII) – so still used for DKA/HHS

• • • Medium-acting – lasts about 6-8 hours
      • Essentially the short acting soluble + a retardant
      • Retardants include Zinc, Crystallised aspart , NPH

• • • Long-acting – used for those with a regular lifestyle
      • 2 main types
        • Insulin glargine (Lantus, Abasaglar )
        • Detemir (levemir),

• • • Mixes – see below
      • Mix a medium– and short- acting agent
        • 2 types of mixes – essentially mix an intermediate + either a short acting soluble or rapid acting analogue
          • Analogue biphasic insulin – a rapid acting analogue + intermediate insulin
          • Human biphasic insulin – short acting soluble insulin (which are human) + a intermediate insulin

• • • There are also ultra fast and ultra long acting that are gaining popularity/being developed
      • E.g. Degludac, an ultra long acting insulin lasting 42 hours

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Regimens:

• • • Different regimes are used depending on the patient’s condition and  activity levels
      • It is important to know these

The Basal-Bolus regimen

1. • The patient takes a long-acting OD/BD + a short-acting before every meal (start 1 unit/10g of Carbs)
2. • Uses:
     • 1st line for type 1 diabetics as it mimics physiological insulin closely
     • Also common in T2DM
       • Allows more flexibility with a variety of meal sizes
         • Used for erratic meals and lifestyle

3. 

Premixed– see mixes

• E.g. humalin m3, humalog mix 25, 50 etc
  • A common example is Novomix
    • Comes in different forms with a different proportion of fast vs medium acting insulin
      • E.g. Novomix 30 = 30% fast-acting insulin aspart + 70% medium-acting aspart
      • 50/50 and 70/30 are also used

• Given in biphasic regimen twice a day before meals and will fulfil both long and short-term needs
  • Dose is titrated to patients BGL at the time  (a sliding scale)

• Used mostly for type 2 diabetics along with oral medications
  • Also 2nd line for T1DM

• Can alternatively manually mix – give both types of insulin separately twice a day
• Advantages over basal-bolus as it is less complex and there is a reduced need for injections
  • Used for those who have a regular lifestyle
  • However it is not as precise

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  Mixed Insulin Regimen

OD long acting

1. • Used any time during the day so long as it’s the same time every day
   • Uses:
     • Used if switching from tablets
     • As an add-on therapy for fairly well-controlled DM with predictable lifestyle
   • However it is very imprecise with lifestyle changes and carries a substantial risk of hypose

QDS regimen

• Ultra-fast acting before meals and long-acting before bed
• Useful as it also allows flexibility for erratic lifestyles

DAFNE – autonomous use of insulin by a trained patient

1. • Usually involves insulin pumps which continuously infuse insulin – only used for type 1 DM (are preferred in these patients)
   • Mainly use a rapid acting analogue insulin, e.g. continuous Actrapid

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Considerations with Insulin

• • •  Side effects – there are 3 key to consider:
      • Hypoglycaemia – especially with elderly patients, alcohol binges, and B blockers (mask Sx)
        • Abort with sugary drinks if patient is still conscious
      • Lipohypertrophy – must rotate injection sites
      • Weight gain

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Patient Education

• • • Several things to consider in education as insulin can be quite problematic

• • • Patient education is important
      1. ADR management – e.g. hypoglycaemia, lipohypertrophy
      2. Self-adjustment of insulin according to exercise and calories
      3. Adjustment during a period of illness – ‘Sick Day Rules‘
         • Illnesses can either raise or drop blood glucose
           • Usually increase insulin requirements
         • Therefore tight monitoring of glucose/ketones, food intake, and adjustment of insulin therapy are key
         • Patients can fall into DKA if they fail to adjust their insulin dose accordingly especially because they will often stop eating on top of this and so decrease their dose
           • This is a key problem in DM1

• • • • Glucose monitoring is useful to inform how much insulin should be given but has it’s limitations
        • Fasting BM only informs long-acting insulin control – not useful for stat dose
        • Finger prick BM after a meal informs short-acting insulin dose

• DVLA
  • Patients on insulin and sulphonylureas must beware the risk of hypose – therefore must take their BGL before driving to be ≥5mmol