this study took place in the women s ambulatory health services ( wahs ) clinic at hartford hospital , an inner - city , tertiary care hospital in hartford , conn . in july 2011 ,
the wahs clinic changed its routine gdm screening from the 50-g , two - step process to the 75-g , one - step process .
routine management included testing all nondiabetic pregnant women for gdm between 24 and 28 weeks gestation .
high - risk women ( patients with a history of gdm or macrosomia or who were obese ) were screened at their initial prenatal visit .
if that screening was negative , they were screened again between 24 and 28 weeks gestation .
using the two - step method , women were considered to have screened positive for gdm if they had a serum glucose value  135 mg / dl 1 hour after the nonfasting 50-g challenge test .
the threshold values used for the ogtt were : fasting  95 mg / dl , 1-hour  180 mg / dl , 2-hour  155 mg / dl , and 3-hour  140 mg / dl , based on the criteria of carpenter and coustan , with two abnormal values required for diagnosis .
women with a 50-g test result > 183 mg / dl were not given the ogtt and were diagnosed with gdm . for the one - step screening ,
the criteria used for this method were based on the hyperglycemia and adverse pregnancy outcome ( hapo ) study .
the threshold values were : fasting  92 mg / dl , 1-hour  180 mg / dl , and 2-hour  153 mg / dl .
all women diagnosed with gdm were treated in a similar manner throughout the study period with dietary modification and/or insulin depending on their capillary blood glucose values .
glucose screening and outcome data from the 9 months ( 1 october 2010 to 30 june 2011 ) preceding the change in screening method were collected and compared to data from the first 6 months ( 1 july 2011 to 31 december 2011 ) of the one - step screening process . for patients who had glucose testing performed at the end of the study period ,
data collection continued for an additional 3 months ( 1 january 2012 to 30 march 2012 ) to include delivery outcomes .
included records were those of female patients  18 years of age who were seen at the wahs clinic during the allotted time period .
excluded records were those of female patients who were < 18 years of age , had preexisting diabetes , or had a history of gastric bypass surgery .
maternal data included race , bmi , weight gain during pregnancy , and mode of delivery .
neonatal outcomes included birth weight , apgar score , neonatal intensive care unit ( nicu ) admission , small - for - gestational - age ( sga ) status , large - for - gestational - age ( lga ) status , hypoglycemia , hyperbilirubinemia , respiratory distress syndrome ( rds ) , intraventricular hemorrhage , culture - proven sepsis , and necrotizing enterocolitis ( nec ) .
data were compared using student s t test ,  test , and fisher s exact test .
a total of 832 patients delivered during the study period ; 10 had preexisting diabetes , 1 had a history of gastric bypass , and 9 were < 18 years of age , leaving 812 patients meeting inclusion criteria .
no differences were found between the two groups regarding average bmi , prepregnancy weight , parity , pregnancy weight gain , or race . of all study patients ,
60.4% were overweight or obese , 29.1% were overweight with a bmi of 2529.9 kg / m , and 31.3% were obese with a bmi  30 kg / m .
the overall distribution of race was hispanic 74% , african american 16.7% , and caucasian 7% .
the 1-hour , 50-g ( two - step ) screening was performed in 458 patients , and 75 patients ( 16.4% ) required a 3-hour screening .
the 2-hour , 75-g ( one - step ) screening was performed in 257 patients . of the patients who had
the 1-hour screening , 32 ( 7% ) ultimately tested positive for gdm after a 3-hour ogtt .
of the 257 patients who had the 2-hour screening , 30 ( 11.7% ) tested positive .
of the women who were seen during the 1-hour screening period , 49 ( 9.9% ) were not compliant with gdm testing compared to 52 ( 16.4% ) seen during the 2-hour screening period .
with regard to delivery outcome , there were no differences between the two groups for mode of delivery , average birth weight , or apgar score ( table 1 ) .
the rates of nicu admission , sga , lga , rds , nec , hyperbilirubinemia , sepsis , and length of nicu stay were similar between the two groups ( figure 1 ) .
we also evaluated for a difference in composite neonatal outcome among infants admitted to the nicu and did not find a difference between the two groups .
the rate of hypoglycemia was lower during the one - step screening process , but this was not statistically significant ( p = 0.056 ) .
debate continues about the best screening and diagnostic method for gdm . in our high - risk patient population
, we did not find a difference in delivery or neonatal outcomes when the one - step screening was used , despite a 4.7% increase in gdm ( from 7 to 11.7% ) .
others have found an even higher incidence ( ranging from 16 to 27% ) of gdm using the one - step screen and the thresholds proposed by the hapo study and the international association of the diabetes and pregnancy study groups .
the lack of a difference in outcome and a lower - than - expected increase in gdm may be related to decreased compliance with testing .
the one - step screening is less convenient because patients must be fasting , and it takes longer to complete than the nonfasting , 1-hour test for the first part of the two - step testing protocol .
a decrease in compliance may not be seen in other pregnancy populations and would potentially affect delivery or neonatal outcomes .
decreased compliance would likely be seen in similar obstetrical practices with high minority rates and decreased overall health care compliance . although not statistically significant , the rate of hypoglycemia was lower in patients in the one - step protocol . with increased compliance , the rate of hypoglycemia may be lower for women who undergo the one - step screening .
if no other differences in neonatal outcome are seen with the one - step screening , the impact of this may not be considered clinically significant if the infants with hypoglycemia do not require more than minimal intervention or monitoring .
for example , women who are employed may be required to take time off to complete fasting blood work , whereas they could complete the 50-g screening at a more convenient time .
a limitation to this study is a lack of data on compliance with therapy . at wahs ,
women diagnosed with gdm are referred to a nutritionist and instructed to check both fasting and 2-hour postprandial blood glucose levels .
they are started on oral or insulin therapy if their blood glucose is consistently > 95 mg / dl fasting and > 120 mg / dl postprandially .
another limitation is the historical nature of the data collected , although both groups , the health care providers , and the practices were similar throughout the study period .
the one - step , 2-hour screening for gdm appears to be associated with an increased rate of gdm , despite decreased rates of screening , without improving maternal or neonatal outcomes .
an increase in the rate of gdm using the one - step screening would also be expected to increase health care costs by increasing doctor visits , ultrasounds , nutrition and diabetes team counseling , and home glucose testing .
 in briefscreening for gestational diabetes mellitus is controversial . in their high - risk obstetrical practice , 
 the authors did not find a difference in delivery or neonatal outcomes when using a one - step versus a two - step screening process . 
 they did find lower rates of compliance with screening when using the one - step method . 
Research Design and Methods
Results
Conclusion