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Do We Know How to Find Gestational Diabetes Mellitus ?. Pathophysiology. Current Diagnosis Guideline. Discrepancies. Gestational Diabetes Mellitus (GDM).
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Pathophysiology Current Diagnosis Guideline Discrepancies
Gestational Diabetes Mellitus (GDM) A carbohydrate intolerance of varying degrees and severity with onset or first recognition during pregnancy with a probable resolution after the end of pregnancy. Diabetes, glucose intolerance or insulin resistance may have existed before the pregnancy.
Pregnancy Pathophysiology Insulin resistance occurs because the hormonal changes associated with pregnancy partially block the effects of insulin. Insulin resistance causes glucose to be shunted from the mother to the fetus to facilitate fetal growth and development. During the third trimester of pregnancy, insulin resistance increases by 50%.
Pregnancy Pathophysiology Maternal pancreatic beta cells increase insulin secretion almost 3 fold to compensate for increased insulin resistance. If the mother’s pancreas is unable to produce sufficient insulin to overcome insulin resistance, maternal glucose levels increase and GDM occurs. GDM usually disappears after pregnancy because the hormonal changes that caused insulin resistance are no longer present.
Management MedicalNutrition therapy: nutrition restriction and reconstruction Insulin Therapy
Value of Laboratory Screening for GDM Screening, identification and treatment can decrease the morbidity and mortality of GDM. Decreased macrosomia, cesarean birth and birth trauma due to a > 4000g infant. Decreased neonatal hypoglycemia, hypocalcemia, hyperbilirubinemia, polycythemia. Identify women at future risk for diabetes and those with insulin resistance.
Demographics of GDM • Most common medical complication of pregnancy • The prevalencemay range from 1 to 14% of all pregnancies, depending on thepopulation studied and the diagnostic tests employed.
Who Should be Screened Low-risk Group: Requires no glucose testing, but this categoryis limited to those women meeting all of the following characteristics: Age<25 years Weight normal before pregnancy Member of anethnic group with a low prevalence of GDM No known diabetesin first-degree relatives No history of abnormal glucose tolerance No history of poor obstetric outcome
Who Should be Screened High Risk Group: Should undergo glucosetesting as soon as feasible. If they are found notto have GDM at that initial screening, they should be retestedbetween 24 and 28 weeks of gestation. Marked obesity Personal history of GDM Glycosuria A strong family history of diabetes
Who Should be Screened Women of average riskshould have testing undertaken at 24–28 weeks of gestation.
Screening > Fasting plasma glucose 7.0 mmol/l(126 mg/dl) Casual plasma glucose > 11.1 mmol/l(200 mg/dl) Diabetes
< Fasting plasma glucose 7.0 mmol/l(126 mg/dl) Casual plasma glucose < 11.1 mmol/l(200 mg/dl) Two-step or one-step screening approach 1. Glucose Challenge Test (GCT) 2. Oral Glucose Tolerance Test (OGTT)
50g glucose challenge test (GCT)(non-fasting) 1hr If glucose level < 7.2-7.8mmol/l (130-140mg/dl) No further screening needed. If >7.2-7.8mmol/l, proceed to diagnostic oral glucose tolerance test (OGTT). Two-Step Screening Nearly 25 % of women will have a + 1hr GCT, and will need a OGTT.
One-Step Screening Directly proceed to diagnostic oral glucose tolerance test (OGTT). The one-step approachmay be cost-effective in high-risk patients or population.
2-hr 75-g OGTT 9.9 8.1
Skepticism Developed in different population Should we use the same cutoff concentrations? 2 out of 3 or 2 out of 4 thresholds?
Pregnant women (16-20 weeks) (1017) Flow Chart of Study Design Perform 75g test #227 g>7.2 mmol/l at 1hr Perform 100g test (17-21 weeks) #45 GDM. No further testing #182 non-GDM. #790 with g<7.2mmol/l at 1hr #972 pregnant women (26-30 weeks) Perform 75g test #488 with g<7.2mmol/l at 1hr #484 with g>7.2mmol/l at 1hr No further testing Perform 100g test (27-31 weeks)
Cohen index McNemar P<0.001 0.21 30 4 0 disagreement 0–0.2 weak agreement 0.2– 0.4 fair agreement 0.4 –0.8 good agreement 0.8 –1.0 perfect agreement P<0.001 0.18 49 15 Number of diagnosed GDM 100g test 75g test Both 16-21 weeks pregnancy 41 15 11 26-31 weeks pregnancy 60 26 11
Different Approaches Mixed meal tolerance tests The area under the curve of a continuous glucose profile for 3 h Continuous glucose monitoring in the typical home setting for several days Something other than glucose?