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)

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 

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

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

The Basal-Bolus regimen

    • The patient takes a long-acting OD/BD + a short-acting before every meal (start 1 unit/10g of Carbs)
    • 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
  1. Common Basal-Bolus Regimens.

Premixedsee 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
    • Mixed Insulin Regimen

OD long acting

    • 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

    • 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

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

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