Gestational diabetes resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mydah Sajid, MD[2]; José Eduardo Riceto Loyola Junior, M.D.[3]

Synonyms and keywords:

Overview

Gestational diabetes is a common complication that occurs in pregnancy. It is defined as the glucose intolerance that develops during gestation in patients who were not diabetic before pregnancy. The hormones produced during pregnancy increase resistance to glucose. In these patients, the glucose levels are elevated to diabetic range. There are several risk factors for gestational diabetes including obesity, previous history of gestational diabetes, sedentary lifestyle, and significant family history of diabetes. This section provides a short and to the point overview of the gestational diabetes.

Causes

Life-Threatening Causes

There is no known life-threatening cause for gestational diabetes.

Common Causes

Gestational diabetes is caused by the production of placental hormones such as estrogen, cortisol, progesterone, leptin, placental lactogen, and placental growth hormone that increase insulin resistance. This promotes endogenous glucose production and facilitation of transportation of glucose through the placenta to the fetus due to a mild hyperglycemic state. This is compensated by the increased pancreatic beta-cells insulin production through hyperplasia and hypertrophy. Some patients, however, may not have the pancreatic reserve to compensate those hormone's effects, possibly due to previous pancreatic injury. Risk factors for such cases include:

• Increased age;
• High Body mass index;
• Low levels of physical activity;
• African American, Hispanic, Asian, and Native American race;
• Excessive weight gain;
• Advanced maternal age;
• Intrauterine environment (low or high birthweight);
• Family or personal history of gestational diabetes;
• Insulin resistance, such as polycystic ovarian syndrome.

Diagnosis

Shown below is an algorithm summarizing the diagnosis of gestational diabetes according to the American College of Obstetricians and Gynecologists guidelines.

All pregnant women should be screened for GDM at 24 weeks or more of gestation

Two-step screening approach is recommended

50g of oral glucose load is administered to the patient followed by measurement of venous blood glucose level after 1 hour

Blood glucose level equal or higher than 190mg/dl or 10.6mmol/l

Yes

No

100g of oral glucose load is administered to the patient followed by measured of venous blood glucose level after 3 hours

Second screening test not required

Blood glucose level equal or more than 145mg/dl or 8mmol/l

Gestational diabetes mellitus diagnosed when there is an abnormal blood glucose level 2 or more times

Treatment

Shown below is an algorithm summarizing the treatment of gestational diabetes according to the American Diabetes Association guidelines.

Patients with confirmed gestational diabetes

Lifestyle and dietary modification along with regular monitoring of blood glucose levels. Food with low or medium glycemic index along with high intake of fiber, fresh fruits, and vegetables. Frequent small meals are recommended. The patient should have three meals with snacks in between twice a day. An active lifestyle with increased physical activity The patient is advised to monitor blood glucose levels 4 to 7 times each day.

Blood glucose level maintained in the normal range?

Yes

No

No need to initiate hypoglycemic medications.

Step- up approach with administration of hypoglycemic drugs. Insulin is the preferred choice with a starting dose of 0.7-1 unit/kg each day divided in a basal-bolus regimen. Metformin and glyburide can also be used but these drugs cross the placenta barrier and their long-term effects on neonates are unknown.

Dos

• The goals for glycemic control in gestational diabetes are fasting plasma glucose level less than 95mg/dl, one hour and two hour post-meal glucose level less than 140 and 120mg/dl, respectively. The insulin regimen can be adjusted according to the blood glucose level. In women with elevated early morning fasting glucose level, a single dose of intermediate-acting insulin should be administered at night. In females with elevated postprandial glucose levels, rapid-acting insulin should be administered half an hour before meals.
• A single step 75 gram oral glucose tolerance test can be used to diagnose gestational diabetes. The gestational diabetes is diagnosed when blood glucose level is equal or greater than 153 mg/dl . This cut-off criteria increased the prevalence of diabetes among pregnant women in various subpopulations .
• An antenatal fetal monitoring is recommended in gestational diabetes pregnant females starting from 32nd week of gestation.
• Screening tests should be done 4-12 weeks after delivery in gestational diabetes to identify if patients have impaired fasting glucose, diabetes, and impaired glucose tolerance. The screening can be done with a fasting plasma glucose level or a 75gram oral glucose tolerance test. Patients with impaired levels should be referred for medical treatment.

Don'ts

• Different clinical trials and meta-analysis have demonstrated considerable efficacy of metformin and glyburide for the treatment of gestational diabetes. Metformin has shown more efficacy for glycemic controlling compared to insulin in pregnant females. It does not have immediate adverse effects on fetus and neonates but, its long-term effects on neonates are still unclear. Hence glyburide and metformin is only prescribed to pregnant females if they cannot tolerate insulin, it may be a safer option or more adequate due to financial restrictions.

References

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