Insulin regimes in Type 2 diabetes

According to NICE recommendations, NPH (isophane) insulin or a long-acting analogue should be used when initiating insulin in type 2 diabetes patients (1).

In majority of patients there is suboptimal glycaemic control even with initial insulin regiments.

• HbA1C was 7.5% or higher in 74% of patients 6 months after starting insulin therapy
• HbA1C was below 6.5% in only 24% or fewer after 1 year (1).

NICE recommends that in patients whom target HbA1C with the initial regimen is not reached without problematic hypoglycaemia and:

• if on basal regimen should consider additional meal-time doses or switching to a premixed insulin
• if on premixed insulin once or twice daily, it suggests they should consider an additional meal-time injection or change to a basal regimen plus meal-time injections (1).

Some proposed insulin regimes for patients with Type 2 diabetes (2):

• Once Daily – Basal Regimen
  • a basal regimen involves the use of a Neutral Protamine Hagendorn (NPH) or analogue insulin
    • choose an intermediate acting insulin, which provides a low background level of insulin. This may be used to supplement the daytime oral glucose lowering agents
    • human Isophane is the background insulin of choice
      • is no evidence for improved diabetes control with analogue basal insulin in people living with type 2 diabetes
      • analogue basal insulin should only be considered in people living with type 2 diabetes who have recurrent hypoglycaemia or where they require assistance with their insulin injections
      • is usual to calculate daily insulin requirement as 0.5 units / kg body weight approximately, then use 60% of the calculated dose for safety. The calculation below reduces the chance of error
        • daily insulin requirements = 0.3 units / kg body weight approximately e.g. 0.3 x 72kg = 21.6 units (round up to 22 units). Of which 50% will be basal requirement 22 x 50% = 11 units (round up to 12 units)
        • a safe starting dose would be e.g. 12 units of intermediate acting insulin, usually given at bedtime
          
          
• Twice Daily Regimen
  • for twice daily regimens the most frequently used option is a premixed fixed combination of short and intermediate acting insulin or a rapid acting insulin lispro or aspart mix. A twice-daily intermediate acting insulin is an alternative choice and may be appropriate in the elderly where there is a concern regarding the risk of hypoglycaemia.
  • daily insulin requirements = 0.5 units / kg body weight approximately e.g. 0.5 x 72kg = 36 units
  • take e.g. 60% 'for safety' 36 units x 60% = 22 units
  • Split the dose 50%: 50% before breakfast and evening meal. i.e. 11 units bd. Rounded up to 12 units for ease of administration
  • Generally the final insulin dose required will be nearer to 60%/40% divide
    
    
• Basal Bolus Regimen
  • is the most intensive regime with three pre-prandial doses of short /rapid acting insulin and a bedtime dose of intermediate or long acting insulin
    • While this regime offers no improvement in metabolic control compared to any other insulin regime, this may be the most suitable regimen for people who do not have a stable daily routine as the time and dose of insulin can be varied according to when the meal is taken and its carbohydrate content
  • generally 30 - 50% of the total daily insulin requirements should be given as intermediate or long acting insulin at bedtime with the remaining insulin being given as short / rapid acting before breakfast, lunch and evening meal depending on the needs of the individual.
    • Daily Insulin requirements = 0.5 units / kg body weight approximately e.g. 0.5 x 72kg = 36 units
    • Take e.g. 60% 'for safety' 36 units x 60% = 22 units
  • when commencing a basal bolus regimen where three pre-prandial doses of short/rapid acting insulin are to be taken prior to breakfast, lunch and evening meal and intermediate acting/ long acting analogue insulin at bedtime the total daily dose may be calculated as follows;
    • 22 units as above. -50% of the total daily dose is basal = 11 units e.g. 'rounding down' for ease of administration = 10 units
    • Daily bolus insulin dose therefore is 22 -10 (basal dose) = 12 units of short acting insulin.
    • This is divided into 3 for pre breakfast, lunch and evening meal = 4 units each meal. 10 units of intermediate/long acting analogue are given prior to bed
  • insulin can then be increased to the requirement of the individual.

In general, it is beneficial to commence the individual with Type 2 diabetes on a twice-daily insulin regimen initially until they feel comfortable with injections (2).

In consideration as to whether to initiate once or twice daily insulin in type 2 diabetic patients:

• there is study evidence that (3) in subjects with type 2 diabetes poorly controlled on oral hypoglycaemic agents, initiating insulin therapy with twice-daily biphasic insulin aspart 70/30 (prebreakfast and presupper) was more effective in achieving HbA(1c) targets than once-daily glargine, especially in subjects with HbA(1c) >8.5%

Notes (4):

• in consideration of starting dose of insulin - if using analogue rather than human insulin then use a 10% dose reduction as a precaution

Reference:

1. Barnett A et al. Insulin for type 2 diabetes: choosing a second-line insulin regimen. Int J Clin Pract. 2008;62(11):1647-53
2. NHS (Greater Glasgow and Clyde). Guidelines for Insulin Initiation and Adjustment in Primary Care in patients with Type 2 Diabetes: for the guidance of Diabetes Specialist Nurses (accessed 24/7/24)
3. Raskin P et al. Initiating insulin therapy in type 2 diabetes: a comparison of biphasic and basal insulin analogs. Diabetes Care 2005;28:260-5n
4. Novo Nordisk (August 2005). Human to Analogue Transfer Guide.