Treatment Options to Control Blood Glucose |
 |
Treatment Option D: Premixed Human Insulin or Analog Insulin Mix
Human insulin 70/30: this is a premixed insulin that is 70% intermediate-acting insulin (NPH analog) and 30% short-acting insulin (regular).13
Insulin aspart 70/30: premixed insulin that is 70% intermediate-acting insulin analog and 30% of the fast-acting analog aspart. On average, the fast-acting analog component starts to lower blood glucose within 15 minutes after injection with peak action in about 1 hour. The intermediate component peaks in 1 to 4 hours and has a duration of up to 24 hours.14
Insulin lispro 75/25: this is a premixed insulin that is 75% intermediate-acting insulin analog and 25% of the fast-acting analog lispro. It has its strongest effect 30 minutes to 1 hour after injection.15
Action: You prescribe insulin aspart 70/30 mix, 10 units at the start of the evening meal and titrate by phone to 15 units before breakfast and 15 units before supper. When the patient returns, she reports her BG diary:
Table 6. Patient SMBG Diary| Before Breakfast | Before Lunch | Before Supper | After Supper | 2:00 AM |
| 171 mg/dL | 149 mg/dL | |||
| 141 mg/dL | 211 mg/dL | |||
| 207 mg/dL | 51 mg/dL | 115 mg/dL | ||
| 198 mg/dL | 194 mg/dL | |||
| 158 mg/dL | 129 mg/dL | 47 mg/dL |
Comment: This insulin regimen has been effective at lowering Mrs. S’s blood sugar. However, the fasting and pre-meal blood sugars are still above target, and because of postprandial hypoglycemia, the dose cannot safely be increased.
Premixed insulin preparations deliver a mixture of a fast-acting and an intermediate-acting insulin in one injection. This may have the advantage of controlling postprandial hyperglycemia for the meal before which it is administered and of providing some basal coverage, all with the convenience of one injection.
The advantage of an analog mix over the human mixes is that the fast-acting analogs have a rapid onset of action, so they may be administered just before eating and may provide better control of postprandial hyperglycemia.16
There are some potential limitations for the use of insulin mixes, as is seen in this patient:
- An inability to adjust the ratio of the two different insulins, eg, as in this example, where the morning dose of insulin/aspart mix, on occasion, leads to a low BG before lunch, but in general the pre-supper BGs are above goal. Increasing the morning insulin to control the pre-supper BG would exacerbate the tendency to pre-lunch hypoglycemia
- There may be a peak associated with the intermediate-acting component, which may result in hypoglycemia if food is not consumed at the required time (ie, lunch for a dose administered at breakfast and bedtime snack for a dose administered at supper)
- Hyperglycemia may occur, since no fast-acting insulin is provided at lunch
- Morning hyperglycemia may occur when the duration of action of the intermediate-acting component is insufficient
Given these limitations, these insulin mixes are useful for patients who can adhere to regular meal times with a consistent carbohydrate intake at each meal. They are also useful for patients who are unable to mix insulins. Such patients must also have sufficient ß-cell function to release endogenous insulin at lunch time.
Action: Given Mrs. S’s positive response to the insulin aspart 70/30 mix, and given the episode of hypoglycemia, a reasonable approach could well be to lower the dose of insulin concurrent with initiating oral agents.
Back to “Case 1”