It is very possible that several cases of gestational diabetes represent preexisting undiagnosed Type 2 DM. Occurrence of Type 2 DM in pregnancy is considered to have increased in recent years, since this type of diabetes can now be diagnosed at younger ages with increasing frequency. Insulin usage in pregnancy does not allow the easy and precise evaluation of Type 2 DM and this problem is bigger in peoples with a high prevalence of Type 1 DM, such as in Scandinavia. Correspondingly, in peoples with a high prevalence of Type 2 DM, maybe half of all diabetic cases at pregnancy are Type 2.
It should also be noted that complications of pregnant women with Type 2 DM have been recorded, such as diabetic retinopathy and preeclampsia as well as foetal complications, at percentages similar to those of Type 1 DM. The increase in Type 2 DM prevalence in developing and developed countries is expected to increase the percentage of pregnant women with Type 2 DM in the near future.
During prenatal screening, a young woman with diagnosed Type 1 DM monitored at the Diabetes Outpatient Clinic, is enquiring about safety of her pregnancy.
Although complications in neonates of mothers with gestational diabetes are usually minimal, Type 1 DM pregnancies incur a high risk for teratogenesis in the neonate due to hyperglycaemia and other difficulties, especially if the mother suffers from nephropathy, retino-pathy or heart disease.
Gestational complications affect prognosis. Pre-eclampsia, the frequency of which is double in pregnant diabetics compared to non-diabetics, is associated with premature births.
The White classification (Table 10.2) is used for pregnancy prognosis and the risks of DM to the foetus. This classification is based on age at onset and duration of DM, as well as on the presence of complications.
Diabetes and pregnancy 125 Table 10.2. The White classification of diabetes in pregnancy
A Impaired glucose tolerance, at any age, treated only by diet therapy
B Onset of diabetes at age 20 years or older and duration of less than 10 years
C Onset of diabetes at age 10-19 years and duration of
D Onset before 10 years of age, duration over 20 years, benign retinopathy, or hypertension (not preeclampsia) D1 Onset before age 10 years D2 Duration over 20 years
D3 Calcification of vessels of the leg (macrovascular disease)-
formerly called Class E D4 Benign retinopathy (microvascular disease) D4 Hypertension (not preeclampsia) R Proliferative retinopathy or vitreous haemorrhage
F Nephropathy with over 500 mg/day proteinuria
RF Criteria for both classes R and F
G Many pregnancy failures
H Evidence of arteriosclerotic heart disease
T Prior renal transplantation
Classes B through T require insulin treatment Gestational diabetes
A1 Diet-controlled gestational diabetes
A2 Insulin-treated gestational diabetes
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