Insulin Management in Pregnancy

Initial Insulin Requirements and Titration

The American Diabetes Association recommends that insulin is the preferred medication for managing diabetes in pregnancy, with dosing requiring frequent titration as requirements typically double to triple by the third trimester, necessitating either multiple daily injections or continuous subcutaneous insulin infusion 1, 2
Insulin requirements often decrease in the first trimester due to enhanced insulin sensitivity, increasing the risk of hypoglycemia 2, 3
Insulin requirements increase almost linearly between 2 and 9 months gestation, with the most dramatic changes occurring after 16 weeks when insulin resistance begins to increase exponentially 3
By late gestation, total daily insulin requirements typically double to triple compared to pre-pregnancy doses 2

Both multiple daily injections (basal-bolus regimens) and continuous subcutaneous insulin infusion (insulin pumps) are acceptable delivery strategies, with neither shown to be superior 1, 4, 5

Women with type 1 diabetes have increased hypoglycemia risk in the first trimester due to enhanced insulin sensitivity and altered counterregulatory responses 1, 5
Insulin resistance drops precipitously after placental delivery, requiring immediate dose reduction 4, 5
Post-delivery, resume basal-bolus insulin at either 80% of pre-pregnancy doses or 50% of end-of-pregnancy doses 6
Glycemic control is often easier to achieve than in type 1 diabetes, but may require much higher insulin doses, sometimes necessitating concentrated insulin formulations 4, 5, 7

Human insulin preparations that do not cross the placenta are preferred 1, 2
Insulins studied in randomized controlled trials are preferred over those studied only in cohort studies or case reports 1
Current hybrid closed-loop systems do not achieve pregnancy-specific glucose targets, though predictive low-glucose suspend technology reduces hypoglycemia risk 1

Regular evaluation of insulin requirements is necessary every 2-3 weeks as pregnancy progresses 2
A rapid reduction in insulin requirements may indicate placental insufficiency and requires immediate medical evaluation 2, 3
Daily monitoring of fasting and postprandial blood glucose (4-6 times daily) is essential for insulin dose adjustments 3, 6
Target glucose levels: fasting 70-95 mg/dL, 1-hour postprandial 110-140 mg/dL, 2-hour postprandial 100-120 mg/dL 2, 3

Pregnancy is a ketogenic state, and women with type 1 diabetes are at risk for DKA at lower blood glucose levels than when not pregnant 5, 6
Education for patients and family members about prevention, recognition, and treatment of hypoglycemia is essential before, during, and after pregnancy 1, 2
Due to the complexity of insulin management in pregnancy, referral to a specialized center offering team-based care is recommended 1, 7

The American Diabetes Association recommends titrating Lantus to achieve target glucose levels, including fasting glucose of 70-95 mg/dL, one-hour postprandial glucose of 110-140 mg/dL, and two-hour postprandial glucose of 100-120 mg/dL, in pregnant women with diabetes 8
Lantus should comprise a smaller proportion of total daily insulin in pregnancy, with greater emphasis on prandial insulin coverage, as recommended by the American Diabetes Association 9

The British Diabetes Association suggests that if transitioning from pump therapy or requiring subcutaneous basal insulin, the 24-hour basal dose can be replaced with Lantus given in two divided doses 12 hours apart 10

The American College of Obstetricians and Gynecologists notes that insulin glargine is FDA pregnancy category C, though observational studies suggest comparable safety to NPH insulin, as reported by the American Diabetes Association 9
The American Diabetes Association strongly recommends referral to a specialized diabetes and pregnancy center due to the complexity of insulin management in pregnancy 9