Table 4.

Meta‐analysis results for the effects of candidate variants in transporter genes on metformin glycemic response in participants on metformin monotherapy, stratified by metformin dose

SNP	Effect allele	No. of studies	Dose ≤1,000 mg						Dose >1,000 mg
			No. of patients	Beta	SE	P value	I2	P(Q)	No. of patients	Beta	SE	P value	I2	P(Q)
OCT1 R61C	T	5	3,015	0.019	0.038	0.619	0.0	0.855	1,361	0.000	0.000	1.000	0.0	0.719
OCT1 M420del	del	4	2,903	‐0.001	0.050	0.987	55.6	0.080	1,394	0.013	0.040	0.747	44.9	0.142
OCT1 RF allelesa		4	2,690	0.006	0.025	0.812	0.2	0.391	1,296	0.032	0.039	0.412	26.1	0.255
OCT1 rs622342	C	5	3,571	‐0.004	0.019	0.837	0.0	0.523	1,702	0.055	0.030	0.064	0.0	0.679
OCT2 A270S	T	6	3,388	0.013	0.029	0.659	0.0	0.749	1,614	0.062	0.082	0.453	50.9	0.070
MATE1 rs2289669	A	6	3,428	‐0.014	0.018	0.452	38.1	0.152	1,552	0.060	0.030	0.046	20.0	0.282
MATE1 rs2252281	C	4	1,629	0.004	0.026	0.877	0.0	0.750	899	‐0.006	0.031	0.843	32.2	0.219
MATE2 rs12943590	A	6	3,009	‐0.012	0.023	0.592	0.0	0.799	1,264	‐0.070	0.088	0.431	93.1	0.000
OCTN1 T306I	T	6	3,116	0.017	0.020	0.401	0.0	0.728	1,531	0.038	0.033	0.251	0.0	0.971
OCTN1 L503F	T	4	2,889	‐0.044	0.020	0.028	35.8	0.197	1,313	‐0.029	0.036	0.434	48.4	0.121

I², heterogeneity index; MATE, multidrug and toxin extrusion transporter; OCT1, organic cation transporter 1; P(Q), P value for Cochrane's Q statistic; RF, reduced function; SNP, single‐nucleotide polymorphism.

^aCombined genotype for R61C and M420del – number of reduced‐function alleles. A positive beta is a greater glycemic response to metformin associated with the effect allele.