Diabetes in pregnancy

Diabetes in Pregnancy

 

Diabetes in pregnancy is divided into gestational diabetes mellitus (GDM) and pre-gestational diabetes. White’s Classification is used to describe diabetes in pregnancy.

 

White’s Classification of Diabetes Mellitus

Class

Description

A1

DM diagnosed during pregnancy which is diet controlled.

A2

DM diagnosed during pregnancy requiring medication.

B

Insulin-requiring DM diagnosed before pregnancy, after the age of 20, lasting less than 10 years.

C

Insulin-requiring, onset at age 10-19, with duration 10-19 years.

D

Onset before age 10 or duration longer than 20 years, or associated with CHTN or background retinopathy.

F

DM with renal disease.

H

DM with CAD.

R

DM with proliferative retinopathy.

T

DM with renal transplant.

 

Screening and Diagnosis For GDM

If a patient is low risk, then a 50 g, 1 hour glucose screen (GS) is conducted at 28 weeks gestation:

- If < 140, then normal.

- If > 200, then GDM.

- If 140-199, then 3 hour (100 g) Glucose Tolerance Test (GTT):

- If 2 or more of the 4 sample are abnormal, then GDM (F>95, 1hr>180, 2hr>155, 3hr>140).

- If 1 value is abnormal, then patient has insulin resistance and is high risk, so repeat 3 hour GTT in 4 wks.

- If all four values are normal, then normal.

If patient is at high risk, then 1 hour GS at 24 weeks or earlier. Risk factors include marked obesity, history of GDM, strong family history of type 2 DM, PCOS, or multiple gestation.

- If negative, then repeat GS in 4 weeks.

- If positive, then proceed with 3 hour GTT as above.

- If positive prior to 20 wks, then check HgA1c. If this is elevated, then patient likely has preexisting DM and is at higher risk for congenital malformations. If normal, then the patient is treated as a GDM.

 

Management of GDM

If patient is diagnosed with GDMA₁, then start with:

- Diet therapy, at 30 kcal/kg for ideal pre-pregnancy body weight, 35 kcal/kg for underweight patients and 25 kcal/kg for overweight patients.

- Exercise 3-4 times/weeks for 20-30 minutes (brisk walking).

- Fasting and 2 hours postprandial blood sugar checks with documentation of diet.

- Office visits q1-2 weeks.

- If majority of fasting glucose > 95 or 2 hours pp > 120 (or 1 hour >130-140), then patient needs additional intervention:

- If patient not compliant with diet, then reinforce and recheck.

- If patient compliant with diet, but more than half of values elevated, then proceed to pharmacological intervention.

If pharmacological intervention required, then may try Glyburide first:

- Start at 2.5 mg BID

- Proceed up to 10 mg BID

If patient fails Glyburide trial or physician uncomfortable with use, then implement insulin therapy:

- Split dosing of NPH and Regular or Lispro.

- 0.8 U/kg actual body weight in 1^st trimester, 1.0 U/kg in 2^nd, 1.2 U/kg in 3^rd.

- 2/3 of total dose in am (2/3 NPH, 1/3 R/L); then 1/3 in pm (1/2 R/L at dinner, 1/2 NPH at hs).

If patient remains diet controlled, then twice-weekly testing beginning at 40 weeks.

- If pt has HTN or previous fetal loss, then twice-weekly NSTs at 32 weeks.

- If fetus > 4500 grams, then consider cesarean delivery.

- If patient requires Glyburide or insulin, then survey as a pregestational DM with twice-weekly testing beginning at 32 weeks.

- If well controlled, then allow to proceed to due date.

- If poorly controlled, then consider elective delivery at 38-39 weeks (with amniocentesis for FLM if before 39 weeks).

 

Management of Pregestational Diabetes

Infants of mother with pregestational diabetes are at risk for major congenital anomalies including cardiac defects, CNS anomalies, anencephaly, spina bifida, skeletal malformations, sacral agenesis, and spontaneous abortions. The malformation rate is directly related to the HgA1c. The malformation rate is 3.4% for HgA1c less than 8.5%, but up to 22% for HgA1c > 9.5%.

- Patients should be scheduled for retinal examination in the first trimester, with follow-up later in pregnancy if retinopathy is present.

- Patients should have a baseline 24 hour urinalysis for protein and creatinine clearance.

- EKG and echocardiography may be considered, particularly if DM is longstanding or there are other risk factors for CAD.

- Twice-weekly antenatal testing should begin at 32 weeks if on insulin.