Iowa Neonatology Handbook: Metabolic

Metabolic Problems in Infants of Diabetic Mothers (IDM'S)

John A. Widness, MD
Peer Review Status: Internally Peer Reviewed

1. Maternal Factors: The degree of illness in the IDM has been associated with the duration, severity and control of the mother's diabetes. Hence, essential points in the maternal history are:
   
   1. White's Class of diabetes (increasing from "Classes" A->R),
   2. Therapy (diet, insulin, oral hypoglycemic drugs, etc.),
   3. Time of the last insulin injection prior to delivery since this affects maternal glucose,
   4. Amount and type of IV fluids given during labor and delivery,
   5. Estimated gestational age , and
   6. Degree of chronic glucose control during pregnancy by HgbA1c and/or by maternal outpatient glucose "home" monitoring.
      
2. Congenital Anomalies: Because the incidence of congenital anomalies is increased in IDM's, a thorough physical examination is essential. In particular, the incidence of congenital heart disease and anomalies of the nervous system, e.g., anencephaly, spina bifida, microcephaly, caudal regression syndrome, are higher in IDM's. (This knowledge also has important implications in counseling diabetics who have delivered and adolescent girls who have diabetes.)
   
3. RDS: The IDM is at greater risk for RDS than most non-IDM infants of comparable gestational age. During the first hours of life, all IDMs should be observed carefully for this morbidity and treated promptly.
   
4. Hypoglycemia: The incidence of hypoglycemia in IDM’s has been reported as high as 50% in some studies. Optimally, cord blood obtained at delivery should be sent to STAT for a true plasma glucose level. The higher the cord plasma glucose value, the greater the likelihood the infant will develop hypoglycemia within the first hours of life.
   
   The incidence of hypoglycemia is highest at 1-4 hours of age after the fall in plasma glucose following the cessation of maternal glucose infusion (see Figure). In the asymptomatic infant, true plasma glucose should be monitored at 1,2,4,6,9,12, and 24 hours. Because of their inaccuracy, Chemstrips® are not recommended for this purpose. The hypoglycemia in IDM’s is usually transient and easily treated. (See section on hypoglycemia for therapeutic approach.)
   
   All IDM's without respiratory distress should be fed by nipple or gavage by 2 hours of age. If the clinical condition is such that s/he cannot tolerate enteral feedings by 2 hours of age, an IV infusion of D10W should be considered.
   
5. Hypocalcemia: The infant should be monitored for hypocalcemia frequently occuring in the first 24 hours (see section on "Hypocalcemia").
   
6. Polycythemia: A screening capillary hematocrit should be obtained at 4 to 6 hours of life since the incidence of hyperviscosity is higher in IDM's. Values > 65% should be repeated immediately by a peripheral venous ("central") hematocrit. (see section on "Polycythemia/Hyperviscosity").

References:

Cornblath M & Schwartz R. Disorders of Carbohydrate Metabolism in Infancy. (3rd Ed.). Philadelphia:W. B. Saunders, 1991.

Widness JA . Fetal risks and neonatal complications of diabetes mellitus. In Brody SA, Ueland K and Kase N. Endocrine Disorders in Pregnancy. Norwalk, CN: Appleton & Lange,1989:273-297.

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