Table 4.

Effect of sample selection on associations between SNPs and fasting glucose at visit 1: β-coefficients^* (β), standard errors (SE), and p-values, for significant (p< .002) candidate SNP associations, controlled for age, sex, and field center, by sub-sample.

Gene			no prevalent diabetes			prevalent diabetes				combined sample
	SNP	exclusions	β *	SE	p-value	β *	SE	p-value††	p-value†††	β *	SE	p-value††	p-value†††	interaction p-value††††
MTNR1B	rs10830963	none	0.081	0.009	2.9E-21	−0.228	0.198	0.25	0.16	0.069	0.025	0.007	2.0E-5
MTNR1B	rs10830963	medication users†				−0.331	0.196	0.09	0.07	0.067	0.018	0.0002	5.5E-8	3.1 E -11
G6PC2	rs560887	none	−0.068	0.008	1.0E-16	−0.118	0.195	0.55	0.37	−0.091	0.024	2.0E-4	1.8E-7
G6PC2	rs560887	medication users†				−0.048	0.195	0.81	0.77	−0.077	0.017	9.1E-6	3.3E-9	.23
GCK	rs4607517	none	0.068	0.010	1.0E-11	−0.067	0.228	0.77	0.65	0.095	0.030	0.001	1.7E-5
GCK	rs4607517	medication users†				0.005	0.228	0.98	0.72	0.082	0.022	0.001	1.3E-6	.02
GCKR	rs780094	none	−0.046	0.008	1.7E-9	−0.150	0.192	0.44	0.41	−0.073	0.023	0.001	4.0E-5
GCKR	rs780094	medication users†				−0.320	0.188	0.08	0.11	−0.082	0.016	4.7E-7	1.3E-8	.0067
SLC30A8	rs13266634	none	−0.044	0.008	6.0E-8	−0.051	0.190	0.79	0.74	−0.098	0.024	4.5E-5	3.6E-7
SLC30A8	rs13266634	medication users†				−0.079	0.187	0.67	0.73	−0.074	0.017	1.5E-5	1.6E-7	.80
TCF7L2	rs7903146	none	0.0240	0.008	0.003	−0.001	0.186	0.99	0.99	0.127	0.024	1.4E-7	4.9E-9
TCF7L2	rs7903146	medication users†				−0.187	0.190	0.32	0.39	0.059	0.017	.0007	5.3E-5	.0050

^*mmol/l change per 1 increase copy in minor allele

^†users of glucose-lowering medication excluded as described in the methods section; n excluded= 242

^††p-value for the regression of untransformed fasting glucose on genotype

^†††p-value for the regression of log-transformed fasting glucose on genotype

^††††A statistical test to determine if the strength of association between log-transformed fasting glucose and SNP differed between those with and without prevalent diabetes.