Table 3.

The association between years of schooling, risk of T2DM, and HbA1c levels

MR model	Without Steiger filtering			With Steiger filtering
T2DM	SNPs	OR (95%CI)	P-value	SNPs	OR (95%CI)	P-value
IVW§	210	0.75 (0.57, 0.99) a	0.041	195	0.81 (0.62, 1.05)b	0.12
MR-Egger	210	0.81 (0.24, 2.69)c	0.73	195	0.98 (0.31, 3.10)d	0.97
WM	210	0.64 (0.44, 0.92)	0.017	195	0.74 (0.50, 1.11)	0.15
WMBE	210	0.34 (0.11, 1.02)	0.05	195	0.31 (0.09, 0.99)	0.049
HbA1c	SNPs	β (95%CI)	P-value	SNPs	β (95%CI)	P-value
IVW§	184	−0.1639e (−0.2863, −0.0414)	0.009	46	−0.0782f (−0.2584, 0.1019)	0.40
MR-Egger	184	−0.2319g (−0.7198, 0.2560)	0.35	46	−0.0188h (−0.9386, 0.9009)	0.97
WM	184	−0.5048 (−0.6755, −0.3342)	<0.001	46	−0.4422 (−0.7060, −0.1784)	0.001
WMBE	184	−0.7063 (−1.3318, −0.0807)	0.027	46	−0.5886 (−1.1761, −0.0012)	0.05

Notes Effect sizes were per standard deviation (SD) increase in years of schooling (4.2 years). Embolden figures represent significant results.

^aI²=12% (P-value=0.09),

^bI²=0% (P-value=0.95),

^cEgger-intercept = −0.001 (P-value = 0.90),

^dEgger intercept −0.003 (P-value=0.73),

^eI²=31% (P-value<0.001),

^fI²=0% (P-value 0.53),

^gEgger-intercept = 0.001 (P-value = 0.78),

^hEgger intercept −0.001 (P-value=0.90),

^§Represent the main results.

Abbreviations HbA1c: Glycated haemoglobin, IVW: Inverse-variance weighted, MR: Mendelian randomisation, OR: Odds ratio, SNPs: Single Nucleotide Polymorphisms, T2DM: Type 2 diabetes mellitus, WM: Weighted median, WMBE: Weighted mode-based estimates,