Vishwanath Pattan

Endocrinology

Wyoming Medical Center

Disclosure Holdings in Tandem

Non for this Training

Introduction In the United States, 5 to 6 percent of pregnancies—almost 250,000

women—are affected annually by gestational diabetes (GDM)

High risk groups: Severe obesity, strong family history of type 2 diabetes; previous history of GDM or macrosomia, impaired glucose metabolism, or glucosuria

Gestational diabetes mellitus (GDM) Diabetes diagnosed in the second or third trimester of pregnancy that was

not clearly overt diabetes prior to gestation

Maternal effects from GDM Unlike in women with overt diabetes, rates of fetal anomalies do not

appear to be substantially increased in GDM

Women with GDM and elevated fasting glucose levels have increased rates of unexplained stillbirths similar to women with overt diabetes

Fasting hyperglycemia > 105 mg/dL may be associated with an increased risk of fetal death during the final 4 to 8 weeks

Maternal effects from GDM cont. Similar to women with overt diabetes, adverse maternal effects associated

with gestational diabetes include an increased frequency of polyhydramnios, hypertension, preterm labor and cesarean delivery

Fetal effects from GDM The primary effect attributed to gestational diabetes is excessive fetal size

or macrosomia

The perinatal goal is to avoid difficult delivery from macrosomia and concomitant birth trauma associated with shoulder dystocia

In a retrospective analysis of more than 80,000 vaginal deliveries in Chinese women, Cheng and associates (2013) calculated a 76-fold increased risk for shoulder dystocia in newborns weighing ≥ 4200 g compared with the risk in those weighing < 3500 g

Importantly, however, the odds ratio for shoulder dystocia in women with diabetes was less than 2

Hyperglycemia and Adverse Pregnancy Outcome (HAPO) Study

The frequency of newborn birthweight ≥ 90th percentile for gestational age plotted against glucose levels (mg/dL) fasting and at 1-and 2-hr intervals following a 75-g oral -glucose load

LGA = large for gestational age

Newborns described by the HAPO study had an incidence of clinical neonatal hypoglycemia that increased with increasing maternal OGTT values

Frequency of Neonatal hypoglycemia (<35mg/dL) varied from 1 to 2 percent, but it was as high as 4.6 percent in women with fasting glucose levels ≥ 100 mg/dL

Increased incidence of respiratory distress syndrome, hypocalcemia, polycythemia, hyperbilirubinemia

Screening and diagnosis of GDM

One step Strategy Perform a 75-g OGTT, with plasma glucose measurement when patient is fasting

and at 1 and 2 h, at 24–28 weeks of gestation in women not previously diagnosed with overt diabetes

The OGTT should be performed in the morning after an overnight fast of at least 8 h

The diagnosis of GDM is made when any of the following plasma glucose values are met or exceeded:

Fasting: 92 mg/dL (5.1 mmol/L) 1 h: 180 mg/dL (10.0 mmol/L) 2 h: 153 mg/dL (8.5 mmol/L)

Two-step strategy

26y Caucasian female with no prior history of diabetes, who is 8 weeks pregnant, comes to clinic for her 1st antenatal visit.

Her HbA1c is 6.6%

Which of the following is true:

a) She has gestational diabetes

b) She has pre-gestational diabetes

c) She has prediabetes

d) She is nondiabetic

Patient is 28y pregnant female with BMI 40. When should we screen her for diabetes in antenatal clinic, if patient has not been tested before?

a) 1st prenatal visit

b) Between 24-28 weeks gestation

c) 14-18 weeks gestation

d) anytime

When should we test for gestational diabetes (GDM) in antenatal clinic, if patient was tested negative for diabetes at 1st prenatal visit?

a) Between 24-28 weeks gestation

b) 14-18 weeks gestation

c) Anytime

d) No need to retest if negative in 1st trimester

If women has gestational diabetes, she should be tested for persistent diabetes

a) Immediately after delivery

b) 4-12 weeks post-partum

c) 2 weeks post-partum

d) 16 weeks post-partum

If post-partum diabetes screening is negative, women should be screened for diabetes or prediabetes at least

a) Every 3 years

b) Annually

c) Every 2 years

d) Every 5 years

28y female who is 25 weeks pregnant presented to antenatal clinic 2h after breakfast and wants to be screened for GDM

She can be screened for gestational diabetes during the current antenatal visit

a) With 1 step strategy

b) With 2 step strategy

c) With either 1- or 2- step strategy

d) She can be screened only after 1 more week

Two strategies to diagnose GDM 1. “One-step” 75-g OGTT or

2. “Two-step” approach with a 50-g (non-fasting) screen followed by a 100-g OGTT for those who screen positive

In 2013, the National Institutes of Health (NIH) convened a consensus development conference to consider diagnostic criteria for diagnosing GDM

The panel recommended a two step approach to screening that used a 1-h 50-g glucose load test (GLT) followed by a 3-h 100-gOGTT for those who screened positive

ACOG currently supports the two-step approach but most recently noted that one elevated value, as opposed to two, may be used for the diagnosis of GDM

Due to increased red blood cell turnover, A1C is slightly lower in normal pregnancy than in normal non-pregnant women

The A1C target in pregnancy is 6–6.5%

6% may be optimal if this can be achieved without significant hypoglycemia, but the target may be relaxed to ,7% if necessary to prevent hypoglycemia

Glycemic targets ADA recommended targets for women with type 1 or type 2 diabetes and

GDM:

Fasting ,95 mg/dL (5.3 mmol/L) and either

One-hour postprandial ,140 mg/dL (7.8 mmol/L) or

Two-hour postprandial ,120 mg/dL(6.7 mmol/L)

In practice, it may be challenging for women with type 1 diabetes to achieve these targets without hypoglycemia, particularly women with a history of recurrent hypoglycemia or hypoglycemia unawareness

If women cannot achieve these targets without significant hypoglycemia, the ADA suggests less stringent targets based on clinical experience and individualization of care

Lifestyle change is an essential component of management of gestational diabetes mellitus and may suffice for the treatment of many women

70–85% of women diagnosed with GDM can control GDM with lifestyle modification alone

Management

Medical nutrition plan There is no definitive research that identifies a specific optimal calorie

intake for women with GDM or suggests that their calorie needs are different from those of pregnant women without GDM

The food plan should be based on a nutrition assessment with guidance from the Dietary Reference Intakes (DRI)

The DRI for all pregnant women recommends a minimum of 175 g of carbohydrate, a minimum of 71 g of protein, and 28 g of fiber

The American College of Obstetricians and Gynecologists (2013) suggests that carbohydrate intake be limited to 40 percent of total calories

The remaining calories are apportioned to give 20 percent as protein and 40 percent as fat

Pharmacologic Therapy Medications should be added if needed to achieve glycemic targets

Insulin is the preferred first-line medication for treating hyperglycemia in gestational diabetes mellitus as it does not cross the placenta to a measurable extent

Basal insulin needs should be met using rapid-acting insulin via CSII or by using long-acting insulin (e.g., NPH or detemir, which are U.S. Food and Drug Administration [FDA] pregnancy category B)

The rapid-acting insulin analogs for pump therapy that have been studied in pregnancy include lispro and aspart

Oral agents Metformin and glyburide may be used, but both cross the placenta to the

fetus, with metformin likely crossing to a greater extent than glyburide

There is no agreement regarding the comparative advantages and disadvantages of the two oral agents

All oral agents lack long-term safety data

Metformin, when used to treat polycystic ovary syndrome and induce ovulation, need not be continued once pregnancy has been confirmed

Concerns with oral agents Glyburide was associated with a higher rate of neonatal hypoglycemia and

macrosomia than insulin or metformin in a 2015 systematic review

Metformin was associated with a lower risk of neonatal hypoglycemia and less maternal weight gain than insulin in 2015 systematic reviews (37–39); however, metformin may slightly increase the risk of prematurity

Insulin management during labor and delivery Usual dose of intermediate-acting insulin is given at bedtime

Morning dose of insulin is withheld

Intravenous infusion of normal saline is begun

Once active labor begins or glucose levels decrease to < 70 mg/dL, the infusion is changed from saline to 5-percent dextrose and delivered at a rate of 100–150 mL/hr (2.5 mg/kg/min) to achieve a glucose level of approximately 100 mg/dL

Glucose levels are checked hourly using a bedside meter allowing for adjustment in the insulin or glucose infusion rate

Regular insulin is administered by intravenous infusion if glucose levels exceed 100 mg/dL

References Diabetes Care Volume 41, Supplement 1, January 2018

BMJ. 2015 Jan 21;350:h102

J Clin Endocrinol Metab 2015;100:2071–2080

JAMA Pediatr 2015;169:452– 458

Int J Gynecol Obstet 120:249, 2013

Thank you