Table 2.

Univariate heritability estimates of glycaemic response to metformin

	n	Heritability (h2)	95% CI	p value*
HbA1cconcentrations
Baseline HbA1c	2085	29%	−1 to 60	0·048
On-treatment HbA1c	2085	42%	10 to 73	0·0052
Adjusted on-treatment HbA1c	2085	36%	4 to 69	0·011
Response phenotypes
Absolute reduction in HbA1c	2085	23%	−8 to 54	0·074
Proportional reduction in HbA1c	2085	20%	−11 to 51	0·10
Adjusted reduction in HbA1c	2069	34%	1 to 68	0·022
Achieved target HbA1c concentration†	1942	32%	−1 to 64	0·030

^*p values are from likelihood tests of null hypothesis of heritability being 0.

^†The sample size was reduced to 1942 because some patients had a baseline HbA_1c concentration of 7% or lower.