Diabetic complications during pregnancy
Diabetic complications during pregnancy: Excerpt from Professional Guide to Diseases (Eighth Edition)
Pregnancy places special demands on carbohydrate metabolism and causes the insulin requirement to increase, even in a healthy female. Consequently, pregnancy may lead to a prediabetic state, to the conversion of an asymptomatic subclinical diabetic state to a clinical one (gestational diabetes occurs in about 1% to 2% of all pregnancies), or to complications in a previously stable diabetic state.
The incidence of diabetes mellitus increases with age. Maternal and fetal prognoses can be equivalent to those in nondiabetic females if maternal blood glucose is well controlled and ketosis and other complications are prevented. Infant morbidity and mortality depend on recognizing and successfully controlling hypoglycemia, which may develop within hours after delivery. Preconceptual counseling is helpful in optimizing pregnancy outcomes.
Causes
In diabetes mellitus, glucose is inadequately utilized either because insulin isn’t synthesized or because tissues are resistant to the hormonal action of endogenous insulin. During pregnancy, the fetus relies on maternal glucose as a primary fuel source. Pregnancy triggers protective mechanisms that have anti-insulin effects: increased hormone production (placental lactogen, estrogen, and progesterone), which antagonizes insulin’s effects; degradation of insulin by the placenta; and prolonged elevation of stress hormones (cortisol, epinephrine, and glucagon), which raise blood glucose levels.
In a normal pregnancy, an increase in anti-insulin factors is counterbalanced by an increase in insulin production to maintain normal blood glucose levels. However, females who are prediabetic or diabetic are unable to produce sufficient insulin to overcome the insulin antagonist mechanisms of pregnancy, or their tissues are insulin-resistant. As insulin requirements rise toward term, the patient who’s prediabetic may develop gestational diabetes, necessitating dietary management and, possibly, exogenous insulin to achieve glycemic control, whereas the patient who’s insulin-dependent may need increased insulin dosage.
Signs and symptoms
Indications for diagnostic screening for maternal diabetes mellitus during pregnancy include obesity, excessive weight gain, excessive hunger or thirst, polyuria, recurrent monilial infections, glycosuria, previous delivery of a large neonate, polyhydramnios, maternal hypertension, and a family history of diabetes.
Uncontrolled diabetes in a pregnant female can cause stillbirth, fetal anomalies, premature delivery, and birth of a neonate who’s large or small for gestational age. Such neonates are predisposed to severe episodes of hypoglycemia shortly after birth and may also develop hypocalcemia, hyperbilirubinemia, and respiratory distress syndrome.
Diagnosis
The prevalence of gestational diabetes makes careful screening for hyperglycemia appropriate in all pregnancies. A screening 50-gram 1-hour glucose tolerance test is normally performed at 24 to 28 weeks. In addition, women with a history of fetal macrosomia or who may have nongestational diabetes should be formally tested for diabetes with a 3-hour glucose tolerance test.
Confirming diagnosis A 100-gram 3-hour glucose tolerance test confirms diabetes mellitus when two or more values are above normal.
Procedures to assess fetal status include stress and nonstress tests; ultrasonography to determine fetal age and growth; measurement of phosphatidyl-glycerol; and determination of the lecithin-sphingomyelin (L/S) ratio from amniotic fluid to predict pulmonary maturity. The L/S ratio is less useful in diabetic pregnancies and generally requires a ratio of 3.5:1 to confirm fetal lung maturity.
Treatment
Treatment of both the newly diagnosed and the established diabetic is designed to maintain blood glucose levels within acceptable limits through dietary management and insulin administration. Many females with overt diabetes mellitus require hospitalization at the beginning of pregnancy to assess physical status, check for cardiac and renal disease, and regulate diabetes.
For pregnant patients with diabetes, therapy includes:
❑ bimonthly visits to the obstetrician and the internist during the first 6 months of pregnancy; weekly visits may be necessary during the third trimester
❑ maintenance of fasting blood glucose levels at or below 100 mg/dl and 2-hour postprandial blood glucose levels at or below 120 mg/dl during the pregnancy
❑ frequent monitoring for glycosuria and ketonuria (ketosis presents a grave threat to the fetal central nervous system)
❑ weight control (gain not to exceed 3 to 3½ lb [1.4 to 1.6 kg] per month during the last 6 months of pregnancy)
❑ high-protein diet of 2 g/day/kg of body weight, or a minimum of 80 g/day during the second half of pregnancy; daily calorie intake of 30 to 40 calories/kg of body weight; daily carbohydrate intake of 200 g; and enough fat to provide 36% of total calories (however, vigorous calorie restriction can cause starvation ketosis)
❑ exogenous insulin if diet doesn’t control blood glucose levels. Be alert for changes in insulin requirements from one trimester to the next and immediately postpartum. Oral antidiabetic drugs are contraindicated during pregnancy because they may cause fetal hypoglycemia and congenital anomalies.
Generally, the optimal time for delivery is between 37 and 39 weeks’ gestation, although with reassuring antenatal testing and no evidence of macrosomia, 40 weeks or later is also feasible. The insulin-dependent diabetic may require hospitalization before delivery for frequent monitoring of blood glucose levels and prompt intervention if complications develop.
Depending on fetal status and maternal history, the obstetrician may induce labor or perform a cesarean delivery. During labor and delivery, the patient with diabetes should receive continuous I.V. infusion of dextrose with regular insulin in water. Maternal and fetal status must be monitored closely throughout labor. The patient may benefit from half her prepregnancy dosage of insulin before a cesarean delivery. Her insulin requirement will fall markedly after delivery.
Special considerations
❑ Teach the newly diagnosed patient about diabetes, including dietary management, insulin administration, home monitoring of blood glucose or urine testing for glucose and ketones, and skin and foot care. Instruct her to report ketonuria immediately.
❑ Evaluate the patient who’s diabetic for her knowledge about this disease and provide supplementary patient teaching, as she requires. Inform the patient that frequent monitoring and adjustment of insulin dosage are necessary throughout the course of her pregnancy.
❑ Give reassurance that strict compliance to prescribed therapy should ensure a favorable outcome.
❑ Refer the patient to appropriate social service agencies if financial assistance is necessary because of prolonged hospitalization.
❑ Encourage medical counseling regarding the prognosis of future pregnancies.
Book Source Details
- Book Title: Professional Guide to Diseases (Eighth Edition)
- Author(s): Springhouse
- Year of Publication: 2005
- Copyright Details: Professional Guide to Diseases (Eighth Edition), Copyright © 2005 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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