Gestational Diabetes
I. Introduction
a. Pregnancy is accompanied by insulin resistance, which is primarily mediated by
placental secretion of diabetogenic hormones which include growth hormone,
corticotropin-releasing hormone, placental lactogen, prolactin, and
progesterone. These hormones secreted by the placental and other metabolic
changes ensure that the fetus has a sufficient supply of nutrients.
b. Gestational diabetes mellitus then develops in pregnant woman whose
pancreatic function is insufficient to overcome the insulin resistance.
c. Patients with gestational diabetes are at high risk of developing T2DM later in
life.
d. It is recommended to screen pregnant women for gestational diabetes at 24 to
28 weeks of gestation.
e. Fasting glucose is > 92 is diagnostic of gestational DM
f. Usually in the second and third trimesters (less common in the first trimester)
II. Signs & Symptoms
a. Mothers are usually asymptomatic.
III. Physical Exam Findings
a. May present with edema: signs can include polyhydramnios or a large of
gestational age infant (>90th percentile)
IV. Differential Diagnosis
a. Type 1 DM
b. Type 2 DM
c. Insulin resistance
V. Diagnostic Tests/Studies
a. Obtain a random glucose on all pregnant women during the first prenatal visit to check
for preexisting diabetes, then conduct a repeat screening at 24 to 28 weeks
b. Screening consists of administering a nonfasting 50 gram glucose challenge test,
followed by a serum glucose level 1 hour later. If the 1 hour serum glucose value
is greater than 130 mg/ dL, a 100 gram 3 hour glucose tolerance test is performed.
c. 3 hour glucose tolerance test: Glucose concentration greater than or equal to these
values at two or more time points are generally considered a positive test
a. Fasting: 95
b. One hour > 180
c. Two hour > 155
d. Three hour > 140
VI. Treatment
a. Treatment consists of glycemic control.
b. Dietary modifications and regular exercise (as tolerated)
c. Strict blood glucose monitoring (4x daily)
d. Insulin therapy if glycemic control is insufficient with dietary changes.
a. The dose of insulin required to achieve target glucose levels varies among
individuals
b. The goal is fasting glucose <95, a one-hour pp glucose <130-140, and two
hour pp <120
c. Ranging from 0.7 to 2 units per kg
d. NPH/Regular 2/3 in AM and 1/3 in PM
e. Lispro: 0.5-1 units/kg/day (basal +prandial) give <15 minutes before or
immediately after meals (sc injection)
f. Aspart: 0.5-1 units/kg/day (basal +prandial) give 5-10 minutes before
meals (sc injection)
g. If pregnancy is insulin-dependent do weekly fetal heart rate monitoring
e. Metformin and glyburide in patients who refuse insulin therapy.
a. Metformin: Start with 500 PO BID
b. Glyburide: 1.25-20 mg/day PO divided qd-bid
f. Regular U/S to evaluate fetal development.
g. Consider inducing delivery at week 39-40 if glycemic control is poor or if
complications occur.
VII. Patient Education
a. Insulin is a hormone that enables sugar in the bloodstream to enter the cells of the
body, where sugar is the source of energy. All babies and placentas produce
hormones that make the mother resistant to her own insulin.
b. Most pregnant women produce more insulin to compensate and keep their blood
sugar levels normal, but some pregnant women cannot produce enough extra
insulin and their blood sugar level rises. This condition is called gestational
diabetes.
c. Testing for gestational diabetes is usually done between 24 and 28 weeks of
pregnancy.
d. On the day of the screening test, you can eat and drink normally. You will be given
50 grams of glucose in a drink. You should drink the whole amount within a few
minutes. One hour later, you will have a blood test to measure your blood sugar
level. If your blood sugar level is normal, no other tests are done.
e. If you are diagnosed with gestational diabetes, you will need to make changes in
what you eat, and you will need to learn to check your blood sugar level because
this needs to be checked 4 times a day. If making changes to the way you eat does
not work, you will also need to learn how to give yourself insulin injections or take
a pill to lower your blood sugar levels.
VIII. References
“Gestational-Diabetes-Mellitus-Screening-Diagnosis-and-Prevention.” UpToDate,
www.uptodate.com/contents/gestational-diabetes-mellitus-screening-diagnosis-and-
prevention?search=gestational+diabetes&source=search_result&selectedTitle=2~150&usage_ty
pe=default&display_rank=2.
“Gestational-Diabetes-Mellitus-Obstetric-Issues-and-Management.” UpToDate,
www.uptodate.com/contents/gestational-diabetes-mellitus-obstetric-issues-andmanagement?search=gestational+diabetes&source=search_result&selectedTitle=1~150&u
sage_type=default&display_rank=1#H4.
“Gestational Diabetes.” SMARTY PANCE, 12 Jan. 2021, smartypance.com/lessons/complicatedpregnancy/gestational-diabetes/.
“Diabetes Mellitus.” AmbossIcon,
www.amboss.com/us/knowledge/Diabetes_mellitus#Zf247296741a9b91b15b6247efd52f3
bf.
“Gestational-Diabetes-Mellitus-Glycemic-Control-and-Maternal-Prognosis.” UpToDate,
www.uptodate.com/contents/gestational-diabetes-mellitus-glycemic-control-and-maternalprognosis?search=gestational+diabetes&source=search_result&selectedTitle=3~150&usag
e_type=default&display_rank=3#H3874478336.
“Gestational-Diabetes-beyond-the-Basics.” UpToDate, www.uptodate.com/contents/gestationaldiabetes-beyond-thebasics?search=gestational+diabetes+patient+information&source=search_result&selectedT
itle=2~150&usage_type=default&display_rank=2.
Epocrates App.