AD 6th Oct issue | 页面 22

6 OCTOBER 2023

Table 1 . Types of insulin available in Australia , categorised according to their actions

Generic name ( brand name ) Onset Peak Duration Basal ( long-acting insulin )

Detemir 100 units / mL ( Levemir )

Glargine 100 units / mL ( Optisulin )

Glargine 300 units / mL ( Toujeo )

90 minutes 3-8 hours 16-24 hours

1-2 hours No peak 18-24 hours

1-6 hours No peak 24-36 hours

Basal ( intermediate-acting insulin )

Isophane 100 units / mL ( Humulin NPH , Protaphane )

1-3 hours 5-8 hours 10-18 hours

Bolus ( ultra rapid – acting insulin ) Aspart 100 units / mL ( Fiasp ) 5-10 minutes 30 minutes 3-5 hours Bolus ( rapid-acting insulin )

Fixed-dose combination ( rapid-acting plus intermediate-acting insulin )

Aspart / aspart protamine 100 units / mL ( NovoMix30 )

30 % rapid acting and 70 % basal

Start treatment with insulin

Lispro / lispro protamine 100 units / mL ( Humalog Mix25 , Humalog Mix50 )

25 % or 50 % rapid acting and 75 % or 50 % basal

Test for islet autoantibodies

Fixed-dose combination ( short-acting plus intermediate-acting insulin )

Neutral / isophane 100 units / mL ( Humulin 30 / 70 , Mixtard 30 / 70 )

Neutral / isophane 100 units / mL ( Mixtard 50 / 50 )

30 % short acting and 70 % basal

50 % short acting and 50 % basal

Fixed-dose combination ( long-acting plus rapid-acting insulin )

Degludec / aspart 100 units / mL ( Ryzodeg 70 / 30 )

70 % basal and 30 % rapid acting

Islet autoantibody positive

Diagnosis : type 1 diabetes

Islet autoantibody negative

Classification : unclear

Clinical decision on insulin continuation Consider a trial of non-insulin therapy Serially review the diagnosis

PAGE20 The total daily insulin requirement for an adult with type 1 diabetes is usually between 0.5 units / kg and 1.0 units / kg . However , the amount of insulin needed to achieve adequate control of blood glucose levels varies significantly between individuals and is dependent on multiple factors , including blood glucose concentration at the time of dose , residual insulin production , dietary carbohydrate intake and physical activity .

The choice of an insulin regimen is dependent on patient preference , lifestyle , age and comorbidities ( see table 1 ). The usual insulin regimens include either a multiple daily injection ( basal – bolus ) regimen or a continuous subcutaneous insulin infusion ( insulin pump ).

Typically , the basal component ( a long-acting insulin ) composes about 40 % of the total daily insulin dose and is given once or twice daily at the same time ( bedtime or morning ). The dose of basal insulin is initially adjusted by 10-20 % every 3-7 days until target fasting capillary glucose concentrations are achieved .

The bolus component ( rapid-acting or short-acting insulin ) composes about 60 % of the total daily insulin dose and is given either 15 or 30 minutes before each meal , respectively . The dose of bolus insulin is then adjusted by 10-20 % every 3-7 days until either pre-prandial or two-hour post-prandial blood glucose concentrations are achieved .

A pre-prandial dose of insulin can also be calculated on total carbohydrate intake for patients using a ‘ carbohydrate counting ’ technique . An insulin-to-carbohydrate ratio ( ICR ) can be estimated by dividing 400 by the total daily dose ( TDD ) of insulin in units . For example , for a TDD of 40 units of insulin , the ICR is 1:10 . Therefore , for a patient with an ICR of 1:10 , a 50g carbohydrate meal will require five units of pre-prandial bolus insulin .

A supplemental or correction insulin dose is roughly calculated using an insulin sensitivity factor ( ISF ), which is equal to 130 divided by the TDD of insulin in units . For example , the ISF for a patient taking 52 units per day is 2.5 . Therefore , one unit of rapid-acting bolus insulin should reduce the patient ’ s blood glucose concentration by 2.5mmol / L .

Continuous subcutaneous insulin infusions ( CSII , see figure 5 ) use an external battery-driven pump , which

Less than 200pmol / L

contains an insulin reservoir and continuously delivers rapid-acting insulin at a basal rate via a subcutaneous cannula based on programmed settings .

17 , 18

The patient initiates delivery of bolus doses immediately before meals . The advantages of using a pump include an average HbA1c reduction of about 0.4 % more than a basal – bolus insulin regimen and a lower incidence of nocturnal hypoglycaemia . 19 Some CSII pumps are linked with a subcutaneous continuous glucose monitor ( CGM , see figure 6 ), which can automatically adjust the infused insulin doses based on feedback from a patient ’ s current interstitial glucose levels . All patients with a CSII pump must have a written emergency action plan ( see figure 7 ) and access

200-600pmol / L Retest after five years

Figure 4 . Guidelines for the diagnosis of adult-onset type 1 diabetes .

to both long- and short-acting insulin in case of disrupted insulin delivery from their pump to avoid diabetic ketoacidosis .

The initiation of insulin should always be linked to comprehensive , evidence-based education and training that will ultimately lead to developing attitudes , beliefs , knowledge and skills for effective self-management .

MONITORING GLUCOSE CONTROL

IN adults with type 1 diabetes , cumulative exposure to elevated blood glucose levels is associated with an increased risk of complications , including atherosclerotic cardiovascular disease , heart failure , kidney disease , neuropathy , eye

Test C-peptide ( after longer than three years from diagnosis )

Greater than 600pmol / L

Diagnosis : type 2 diabetes

and foot disease and premature mortality . 20 , 21 Achieving and maintaining optimal glucose control is associated with improved clinical outcomes in adults with type 1 diabetes . 20 , 21 What is optimal may be different for different individuals and should always take into account patient factors , such as their daily activity , history of hypoglycaemia , occupation , comorbidities and personal goals .

HbA1c is routinely measured on blood tests and reflects the average blood glucose level over the previous 10-12 weeks , such that the average blood glucose level approximates to [ 2 x HbA1c (%)] - 4 . HbA1c testing is subsidised by Medicare for testing every three months , but in individuals with stable therapy and glucose levels ,