Universal screening for gestational diabetes becomes easier

Published in The Hindu on August 26, 2009


Universal screening of pregnant women for gestational diabetes (GDM) has got a shot in the arm. Women will no longer have to undergo oral glucose tolerance test (OGTT) on an empty stomach. According to a study published in the journal Acta Diabetologica, gestational diabetes can be picked up with a 75 g glucose challenge test conducted during any time of the day and irrespective of the time of last meal.

“A test has to be causal, reliable and easy on the pregnant women for successful implementation of universal screening,” said Dr. V. Balaji. “Our protocol meets all these requirements.” Dr. Balaji is a Senior Consultant at the Chennai based Dr. V. Seshiah’s Research Institute and Dr. Balaji Diabetes Care Centre.

According to the protocol suggested by the authors, pregnant women should be given 75 g of oral glucose immaterial of the time of the last meal and the blood glucose level checked after two hours.

The rationale is simple. “Whether fasting or after a meal, the blood glucose level should remain normal when challenged [with 75 g oral glucose] if a woman has no abnormality,” said Dr. Balaji. “If the woman has an abnormality, it can be picked up even in a non-fasting state.”

The authors who conducted the trial on 800 pregnant women, challenged them with oral glucose using both the conventional protocol recommended by the WHO and the new criteria.

“The same women showed abnormality [gestational diabetes] when subjected to the WHO criteria and the new protocol,” said Dr. Balaji.

The results clearly demonstrate that doctors can test women for gestational diabetes either in fasting or after-meal conditions.

Detecting gestational diabetes in a community level screening becomes easier when the abnormality can be picked up even in a non-fasting state.

Early screening

The study once again revealed the importance of early screening for gestational diabetes. Although the usual recommendation for GDM screening is between 24 and 28 weeks of gestation, the latest study has once again shown that GDM can be picked up if testing is done during all trimesters.

87 of the 800 women (10.89 per cent) who had GDM, about 8 per cent were picked up when screening was done between 16 and 20 weeks of gestation. Another 19.5 per cent (of the 87 women) were diagnosed between 21 and 24 weeks of gestation. Screening between 29 and 32 weeks of gestation picked up another 16.1 per cent of women.

Previous studies undertaken by the same authors had shown the importance of starting the screening early and doing it every trimester.

A paper published in 2008 in the journal Diabetes Research and Clinical Practice showed that 87 of the 207 who had GDM, nearly 62 per cent (of the 87 women) were picked up prior to 24 weeks. Another 20 per cent of 87 women with the condition were picked up after 28 weeks of gestation.

Another study by the same authors in 2007 in the journal Diabetes Research and Clinical Practice found that of the 16.3 per cent of women who had gestational diabetes, nearly 39 per cent (of 16.3 per cent) were picked up when screening was done before 24 weeks of gestation.

“Screening should start early and any women picked up early and treated appropriately would have better outcome,” he said. Women with normal glucose during the first visit should be tested during subsequent visits as there is a possibility that they would develop GDM at a later stage. “Screening should be done during every trimester,” Dr. Balaji said.

Gestational diabetes in the mothers primes the foetuses; these children are more prone to developing diabetes at a later stage. Early screening and care could also reduce complications in women with gestational diabetes.