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MS WordPerinatologist Corner - C.E.U/C.M.E. Modules
Diabetes In Pregnancy Series
Sponsored by The Indian Health Service Clinical Support Center
PART 2: Management, delivery, and postpartum
5. How to start insulin therapy
Case continued
Ms Kanulie agrees to insulin therapy and you and she decide that to start “two shots a day” would work most conveniently for her.
The total dose of insulin is usually calculated by weight:
- Current pregnancy weight in kilos x 0.5-1.0 units/kg = total daily dose
So for her, starting low: 187 pounds = 85 kg x 0.5 units = 42 units total/day.
Since the diurnal variation of the diabetogenic hormones of pregnancy results in their being secreted in higher concentration in the morning (referred to as “the dawn phenomenon”), 2/3 of the total dose is usually given in the morning, and 1/3 in the evening base on a total dose of 42 units:
- 42 units/d x 2/3 = 28 units in AM
- 42 units/d x 1/3 = 14 units in PM
It is usually split by giving 2/3 as NPH and 1/3 as regular:
- 28 x 2/3 = 18 units NPH + 10 units regular in AM and
- 14 x 1/3 = 10 units NPH + 4 units regular in PM
How to start insulin therapy
These are only starting guidelines and the patient’s response will guide dosage adjustments. She should be seen at least weekly if possible until the dosages chosen keeps all the fasting glucoses <95 and all the post-prandials <120.
Increase the evening NPH to control the fasting glucose but remember “the Somogyi effect”, whereby too much evening insulin may cause hypoglycemia during the night with rebound morning overshoot. If the fasting glucose levels are hard to control despite increasing evening NPH, have the patient check a 2 AM sugar to see if this is occurring. As pregnancy advances and the effect of the “diabetogenic hormones of pregnancy” increases, one can anticipate increasing insulin requirements, and the patient should be reassured that this is the norm.
