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Alternative to bolus insulin when target HbA1c not reached on basal insulin despite fasting glucose levels < 7 mmol/L and/or doses of 0.5 units/kg/day of basal insulin
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Should only be used if the patient is eating regular meals - NB: Important to check kai/food security (can use NZ Health Equity test)
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Currently available premixed insulins in New Zealand include:
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NovoMix 30 (30% rapid acting insulin/70% basal insulin)
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Humalog Mix 25 (25% rapid acting insulin/75% basal insulin)
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Humalog Mix 50 (50% rapid acting insulin/50% basal insulin)
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PenMix 30 (30% short acting insulin/70% basal insulin)
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Humulin 30/70 (30% short acting insulin/70% basal insulin)
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The choice of premixed insulin is dependent on the desired insulin profile for the patient. Premixed insulins containing rapid acting insulin are generally preferred due to the reduced risk of delayed hypoglycaemia. Humalog Mix 50 may be useful when the premixed insulin is administered with a large carbohydrate based meal, particularly if significant persistent postprandial hyperglycaemia with the 25% or 30% mixes.
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Start once daily premixed insulin if predominantly one large meal per day
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Convert daily dose of basal insulin to premixed insulin before largest meal
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Monitor glucose levels before and 2-3 hours after that meal via capillary blood glucose levels or continuous glucose monitoring
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If adherent and correct injection technique, increase dose by 10% if on 3 checks glucose levels rise by > 3 mmol/L with meal AND fasting glucose level is > 10 mmol/L
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NB: Dose changes can be made every 3 consecutive checks i.e. every 3 days if needed
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Start twice daily premixed insulin if multiple meals per day
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Convert daily dose of basal insulin to premixed insulin with half the dose pre-breakfast and half pre-dinner
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Consider alternative ratio if large difference in meal sizes (e.g. 2/3rd of total daily insulin at larger meal and 1/3rd of total daily insulin at smaller meal) and lower evening dose in elderly
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Monitor glucose levels before and 2-3 hours after breakfast and dinner via capillary blood glucose levels or continuous glucose monitoring
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If adherent + correct injection technique then:
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Increase breakfast dose by 10% if on 3 checks glucose levels rise with breakfast by > 3 mmol/L AND pre-dinner glucose is > 10 mmol/L
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Increase dinner dose by 10% if on 3 checks glucose levels rise with dinner by > 3 mmol/L AND pre-breakfast glucose level is > 10 mmol/L
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NB: Dose changes can be made every 3 consecutive checks i.e. every 3 days if needed
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NB: Premixed insulin needs to be mixed by gently inverting before each use
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Stop sulfonylureas once established on premixed insulin, but continue lifestyle management and other glucose lowering therapies
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Provide clear instructions for patients on how to self-titrate and administer premixed insulin
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Clear instructions for patients on how to administer and self-titrate bolus insulin
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Essential particularly if concerns over cognitive impairment (medication oversight may be required)
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Administer before meals
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Patients should be advised that they will likely need to reduce the dose of premixed insulin if they are having significantly less than normal intake at that meal
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Patients should have different coloured pens for their different types of insulin
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Use BD fine 4 or 5 mm needles as associated with better absorption and less pain/trauma
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Encourage rotation of injection sites
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Explain that doses of premixed insulin may need to be reduced for meals immediately before and after strenuous exercise
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Memory adjuncts (e.g. NovoPen Echo; InsulCheck etc.) may be useful
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Consider referral to dietitian for ‘carbohydrate awareness’ and matching of insulin to carbohydrate intake
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If HbA1c remains above target:
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Consider switching one or both injections to Humalog Mix 50 if significant postprandial hyperglycaemia and titrate as above
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Consider adding in bolus insulin at other meals if glucose levels rise by > 3 mmol/L at these times (e.g. lunch, large snacks)
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If the patient remains above target then:
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Ensure adherence to all therapy
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Review lifestyle management and provide ongoing support to improve this
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Check injection technique and injection sites
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Re-refer to dietitian
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Optimise non-insulin glucose lowering therapies
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Strongly consider converting to basal bolus regimen particularly if problems with hypoglycaemia and/or irregularity in diet
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Screen for depression and diabetes distress
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Converting from premixed insulin to basal bolus regimen
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Convert daily dose of premixed insulin to 50% as once daily basal insulin and 50% as bolus insulin split between meals
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E.g. Premixed insulin 25 units mane 35 units nocte → 30 units basal insulin nocte + 10 units of bolus insulin with meals
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May need to alter starting doses of bolus insulin based on different meal sizes across the day
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Titrate doses of basal and bolus insulin as required
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The doses of premixed insulin will likely need to be reduced if major changes in diet (e.g. Ramadan) or if new glucose lowering therapies are added to the regimen