Table 1: Characteristics of studies included in this meta-analysis.

Study IDCountryStudy designBetatrophin
(Elisa kit)
Case definitionControl sourceNumberaAge, yrsbFemale, %cBMI, kg/mBaseline matchingNOS

Ebert et al. (non-CD), 2014 [12]GermanyCCSTotal (Phoenix)T2DM on ADTNondiabetic30/3063/6346.7/63.329.1/28.2NA7

Ebert et al. (CD), 2014 [12]GermanyCCSTotal (Phoenix)T2DM on ADT and CDNondiabetic with eGFR >50 mL/min/1.73 m232/2868/5937.5/46.427.9/25.2NA7

Fu et al., 2014 [11, 19]USACCSTotal (Phoenix)T2DMNondiabetes14/1549.2/46.164.3/60.026.8/26.2BMI, age4

Fenzl et al., 2014 [20]AustriaCCSFull-length (EIAAB)Obese T2DM on ADTObese nondiabetes18/1959.9/56.944.4/47.432.2/35.2BMI, sex, and age7

Chen et al., 2015 [14]ChinaCCSFull-length (EIAAB)Newly diagnosed T2DM without ADTNGT from REACTION study112/13760.7/60.248.2/54.723.4/23.0BMI, sex, age, and blood lipid8

Espes et al., 2014 [21]SwedenCCSFull-length (EIAAB)T2DM on ADTNondiabetes recruited through advertising27/1861.9/65.437.0/50.030.1/29.0BMI, sex, and age7

Hu et al., 2014 [15]SpainCCSFull-length (EIAAB)Newly diagnosed T2D without ADTHealthy participants83/8348.4/48.037.3/34.925.1/25.3Sex, age6

Gómez-Ambrosi et al., 2014 [13]SpainCCSFull-length (Cusabio)Newly diagnosed obese T2DM without ADTObese NGT15/7549.2/47.353.3/49.339.0/39.4NA7

Yamada et al., 2015 [16]JapanCCSFull-length (EIAAB)T2DM on ADTHealthy participants30/1256.0/55.650.0/41.725.7/22.7Sex, age5

Guo et al. (obese), 2015 [22]ChinaCCSFull-length (Aviscera Bioscience)Obese T2DMObese NGT19/2045.4/40.842.1/50.033.5/33.0NA5

Guo et al. (overweight), 2015 [22]ChinaCCSFull-length (Aviscera Bioscience)Overweight T2DMOverweight NGT23/2350.7/49.456.5/56.528.0/27.1NA5

Guo et al. (lean), 2015 [22]ChinaCCSFull-length (Aviscera Bioscience)Lean T2DMLean NGT14/1758.2/46.435.7/47.121.5/22.4NA5

ADT: antidiabetic treatment; BMI: body mass index; CCS: case-control study; CD: chronic hemodialysis; eGFR: evaluated glomerular filtration rate; NA: not available; NGT: normal glucose tolerance; NOS: the Newcastle-Ottawa Scale; T2DM: type 2 diabetes mellitus.
aThe number of cases/number of controls.
bMean age of cases/mean age of controls.
cPercentage of females in cases/percentage of females in controls.
dMean BMI of cases/mean BMI of controls.