TABLE 5.

Caffeinated coffee consumption in relation to plasma SHBG levels and type 2 diabetes stratified by SHBG SNPs

SHBG genotype
	rs6259				rs6257
	GG (wild type)		AG or AA (variant)		CT or CC (variant)		TT (wild type)
Plasma SHBG levels (nmol/l)*	n		n		n		n
Caffeinated coffee intake
Low (<2 cups per day)	277	23.2 (16.6–32.5)	70	23.3 (16.4–32.9)	69	20.3 (14.2–29.0)	285	23.2 (16.6–32.4)
High (≥2 cups per day)	246	24.4 (17.4–34.3)	76	27.8 (19.4–39.7)	72	21.6 (15.2–30.8)	244	25.2 (17.9–35.4)
P for interaction†	0.18				0.84

ORs‡	(Case subjects/control subjects)		(Case subjects/control subjects)		(Case subjects/control subjects)		(Case subjects/control subjects)
Caffeinated coffee intake
Low (<2 cups/day)	152/125	1.00 (reference)	40/30	0.90 (0.40–2.00)	42/27	1.00 (reference)	149/136	0.41 (0.19–0.88)
High (≥2 cups/day)	122/124	0.70 (0.42–1.16)	26/50	0.54 (0.26–1.11)	34/38	0.40 (0.16–1.02)	109/135	0.38 (0.18–0.83)
P for interaction†	0.79				0.13

Data are OR (95% CI) and n.

*The multivariate-adjusted geometric mean SHBG levels with 95% CIs for combinations of SHBG genotypes and caffeinated coffee intake levels (≥2 vs. <2 cups/day) adjusted for matching factors, smoking status, physical activity, family history of diabetes, alcohol use, total calories, and BMI.

†Wald tests were used to test for statistical interaction by entering product terms into the regression models.

‡The multivariate-adjusted ORs and 95% CIs of type 2 diabetes risk for combinations of SHBG genotypes and caffeinated coffee intake levels (≥2 vs. <2 cups/day) adjusted for matching factors, smoking status, physical activity, family history of diabetes, alcohol use, total calories, and BMI.