Pregnancy and Diabetes

Meticulous metabolic control of the diabetes and careful medical and obstetric management is required.

Gestational diabetes

This term refers to glucose intolerance that develops in the course of pregnancy and usually remits following delivery. The condition is typically asymptomatic. Women who have a previous history of gestational diabetes, older or overweight women, those with a history of large for gestational age babies and women from certain ethnic groups are at particular risk, but many cases occur in women who are not in any of these categories. For this reason some advocate screening of all pregnant women on the basis of random plasma glucose testing in each trimester and by oral glucose tolerance testing if the glucose concentration is, for example, 7 mmol/L or more. There is no consensus concerning the level of blood glucose which is harmful for the baby, and therefore no consensus concerning cut- off levels for screening and intervention.


Treatment is with diet in the first instance, but most patients require insulin cover during the pregnancy. Insulin does not cross the placenta. Many oral agents cross the placenta and are usually avoided because of the potential risk to the fetus.
Gestational diabetes has been associated with all the obstetric and neonatal problems described above for pre existing diabetes, except that there is no increase in the rate of congenital abnormalities. It is likely to recur in subsequent pregnancies. Gestational diabetes is often the harbinger of type 2 diabetes in later life. Not all diabetes presenting in pregnancy is gestational. True type 1 diabetes may develop, and swift diagnosis is essential to prevent the development of ketoacidosis. Hospital admission is required if the patient is symptomatic, or has ketonuria or a markedly elevated blood glucose level


Treatment of diabetes in pregnancy

The patient should perform daily home blood glucose profiles, recording blood tests before and 2 hours after meals. The renal threshold falls in pregnancy, and urine tests are therefore of little or no value. Insulin requirements rise progressively, and intensified insulin regimens are generally used. The aim is to maintain blood glucose and fructosamine (or HbA1c) levels as close to the normal
range as can be tolerated.

The patient is seen at intervals of 2 weeks or less at a clinic managed jointly by physician and obstetrician. Circum stances permitting, the aim should be outpatient management with a spontaneous vaginal delivery at term.

Retinopathy and nephropathy may deteriorate during pregnancy. Expert fundoscopy and urine testing for protein should be undertaken at booking, at 28 weeks and before delivery.

Obstetric problems associated with diabetes

Poorly controlled diabetes is associated with stillbirth, mechanical problems in the birth canal owing to fetal macrosomia (large baby), hydramnios (Excess water) and pre-eclampsia. Ketoacidosis in pregnancy carries a 50% fetal mortality, but maternal hypoglycaemia is relatively well tolerated.

Neonatal problems (Problems of new born) associated with diabetes

Maternal diabetes, especially when poorly controlled, is associated with fetal macrosomia. The infant of a diabetic mother is more susceptible to hyaline membrane disease (Respiratory distress following delivery) than non-diabetic infants of similar maturity. In addition, neonatal hypoglycaemia (Low blood sugar) may occur. The mechanism is as follows: maternal glucose crosses the placenta, but insulin does not; the fetal islets hyper secrete insulin to combat maternal hyperglycaemia, and a rebound to hypoglycaemic levels occurs when the umbilical cord is severed. These complications are due to hyperglycaemia in the third trimester. Poor glycaemic control around the time of conception carries an increased risk of major congenital malformations. When a pregnancy is planned, optimal metabolic control should be sought before conception.