Review Article

Plasma Levels of Free Fatty Acids in Women with Gestational Diabetes and Its Intrinsic and Extrinsic Determinants: Systematic Review and Meta-Analysis

Table 1

Characteristics of included studies.

AuthorYearCountryType of studyInclusion criteriaExclusion criteriaDiagnostic criteria for gestational diabetesGestational age at enrollmentStudy populationWomen with GDMMean pre-gestational BMI (Kg/m2)Mean maternal age (years)Mean fasting plasma glucose (mg/dL)Mean fasting plasma insulin (uIU/mL)

Metzger1980USACross-sectionalWomen with gestational diabetes (fasting plasma glucose within the normal range for pregnancy or greater than 105 mg/dl) or normal carbohydrate metabolism.NoneOne-step: 100g
Fasting blood glucose ≥ 100 mg/dL; 1h ≥ 170 mg/dL; 2h ≥ 120 mg/dL; 3h ≥ 110mg/dL.
30-39 w2113N/S28.0696N/S

Buchanan1990USANested case-controlOver-weight pregnant women (pre-pregnancy weight > 120% of ideal) without gestational diabetes mellitus or weight-match pregnant women with gestational diabetes.Receiving exogenous insulin treatment before the study.
Pre-pregnancy complications.
Ingesting medications other than vitamins or iron.
Two-steps: First step; 50g. Second step: 100g cut point values, fasting 105 mg/dL; 1h: 190 mg/dL; 2h 165 mg/dL; 3h 145 mg/dL.30-36 w2010N/S28.3N/S24.5

Lunell1992SwedenCase-controlPregnant women from the antenatal clinic in Kuwait City, where the indications for an oral glucose tolerance test were diabetic heredity of the first degree, the birth of a baby above 4500g or glucosuriaKnown diabetic before their pregnancy. Taking medicines known to affect glucose tolerance.Two-steps: First step; 50g. Second step: cut point values 2h: 5.8 mmol/l or 8.9 mmol/l over some other time point30-34 w443231N/S78.5513

Meyer1996New ZealandNested case-controlWomen in the Illawarra area tested for GDM at the beginning of the third trimesterNoneOne-step:
75g; 2-hour: >8.0 mmol/l
Beginning of the third trimester804425.727N/S10.9

Pappa2005GreeceCase-controlNormal adult non-pregnant women, normal pregnant women with uncomplicated pregnancy or women with gestational diabetes mellitus.Inborn errors of metabolism, epilepsy, chronic renal failure.
Problems that could interfere with measurement.
Two-steps: First step; 50g. Second step: 100g cut point values, fasting 105 mg/dL; 1h: 190 mg/dL; 2h 165 mg/dL; 3h 145 mg/dL.30-33 w1193325.4828N/SN/S
Tsai2005ChinaNested case-controlSingleton pregnancies
Positive diabetic screening test result at 24 to 31 weeks’ gestation
From Taipei’s Municipal Women´s and Children´s Hospital and followed until delivery
Hypertension, hyperlipidemia, renal or liver disease, heart disease, thyroid disorder, pre-gestational diabetes mellitus, and multifetal pregnancy.Two-steps: 50-g oral glucose; >7.8 mmol/l.
Fasting 75g; >5.3
1h: 10.0 mmol/l; 2h: 8.6 mmol/l.
24-31w25321922.331.686.4810.5

Bomba-Opon2006PolandCase-controlPregnant women From Outpatient Clinic at the 1st Department of Obstetrics and Gynecology Warsaw University School Medicine with or without gestational diabetesNoneTwo-steps: 50 g if >139 mg/dL mmol/L, 75g.
Cut values:
Fasting>100 mg/dL, 1h >179 mg/dL, 3h >139 mg/dL
29.7w915224.428.8N/SN/S

Pappa2007GreeceCase-controlPregnant women with uncomplicated pregnancy and women with gestational diabetes at 30-33 weeks of gestation
Singleton pregnancy.
Inborn errors of metabolism, epilepsy, chronic renal failure.
Problems that could interfere with measurements.
Two-steps: 50-g oral glucose; 1 h:> 130 mg / dl (7.2 mmol /l)
Fasting 100g; 1h: 10.0mmol; 2h: 8.6mmol/l; 3h: 7.8mmol/l.
30-33w712525.427.8N/SN/S

Idzior-Walum2008PolandCross-sectionalPregnant women referred to the outpatient diabetic clinic with suspicion of gestational diabetesNoneTwo-steps: 50-g oral glucose; >7.8 mmol / l)
Fasting 75g; >5.3
1h: 10.0mmol; 2h: 8.6mmol/l;
26-32w614427.828.382.8713.5

Xu2015ChinaCase-controlPregnant women with prenatal examinations and a cesarean section and delivered a single full-term healthy child.Women with cardiovascular disease, endocrine disease, renal disease, hepatic disease, complications of gestation or any other disease conditions.Fasting plasma glucose > 5.1 mmol/l and/or a 1-h glucose > 10.0 mmol/l and/or 2-h glucoseBefore delivery1215521.2431.2381.978.57

Zhang2017ChinaCross-sectionalChinese pregnant women with detailed visits for prenatal care in Hangzhou, ChinaPreexisting diabetes, overt thyroid disorder, endocrinopathies, renal insufficiency, corticosteroid therapy, or known fetal anomaly.One-step: 75g
Fasting blood glucose ≥ 5.1 mmol/l; 1h ≥ 10.0 mmol/l; 2h ≥ 8.5 mmol/l.
24-28 w77998N/S27.8376.93N/S

Layton2019CanadaNested case-controlPregnant women with data in the Genetics of Glucose regulation in Gestational and Growth (Gen3G) cohort.
First trimester through delivery
Women with pre-existing diabetes at enrolment.One-step:
75g
Fasting blood glucose ≥ 92 mg/dL; 1h ≥ 180mg/dL; 2h ≥ 153 mg/dL.
Second trimester8056724.1628.08N/S7.63

N/S: not stated; USA: United States of America; w: weeks; h: hours; IU: international units; mg/dL: milligrams over deciliters; mmol/L: millimoles over liters.