A common polymorphism near the interleukin-6 gene modifies the association between dietary fat intake and insulin sensitivity

Figures & data

Table 1 Clinical and metabolic characteristics and dietary intake by rs7801406 genotype*

	rs7801406
	G/G (n = 333)	G/A (n = 305)	A/A (n = 69)	P**
Age (years)	22.6 ± 0.1a	23.1 ± 0.1b	23.1 ± 0.3a,b	0.02
Gender (% female)	61.3%	72.5%	71.0%	0.008
BMI (kg/m^2)	23.1 ± 0.2	23.0 ± 0.2	23.4 ± 0.4	0.67
Smoking status (%)
Never	82.6%	79.7%	85.5%
Past	9.3%	13.4%	2.9%
Present	8.1%	6.9%	11.6%	0.07
Physical activity (MET · hour/week)	8.2 ± 0.2	7.8 ± 0.2	8.6 ± 0.4	0.06
Waist circumference (cm)	76.6 ± 0.5	76.6 ± 0.6	77.7 ± 1.1	0.58
Systolic blood pressure (mmHg)	116.8 ± 0.6	117.3 ± 0.7	118.4 ± 1.2	0.39
Diastolic blood pressure (mmHg)	69.9 ± 0.5	70.2 ± 0.6	69.3 ± 1.1	0.69
Total cholesterol (mmol/L)	4.1 ± 0.05	4.3 ± 0.06	4.2 ± 0.10	0.17
LDL cholesterol (mmol/L)	2.3 ± 0.04	2.3 ± 0.05	2.3 ± 0.09	0.67
HDL cholesterol (mmol/L)	1.5 ± 0.02	1.5 ± 0.03	1.4 ± 0.05	0.40
Triglycerides (mmol/L)	0.94 ± 0.03	1.0 ± 0.03	1.0 ± 0.06	0.19
Free fatty acids (μmol/L)	453 ± 14.9	484 ± 17.3	513 ± 32.4	0.11
hs-CRP (mg/L)	0.5 ± 0.9	0.5 ± 1.0	0.6 ± 1.6	0.49
Glucose (mmol/L)	4.8 ± 0.02	4.8 ± 0.02	4.8 ± 0.05	0.47
Insulin (pmol/L)	52.7 ± 1.7	52.8 ± 2.0	53.0 ± 3.8	0.93
HOMA-IR	1.6 ± 0.05	1.6 ± 0.06	1.6 ± 0.1	0.94
HOMA-β	116.8 ± 4.5	116.0 ± 5.2	113.3 ± 9.8	0.74
Family history of diabetes (%)	14.1%	11.5%	7.3%	0.24
Energy intake (kcal/day)	1989 ± 35.1a,b	1967 ± 36.7a	2187 ± 77.2b	0.03
Total fat (% energy)	30.0 ± 0.4	30.0 ± 0.4	31.0 ± 0.8	0.52
SFA (% energy)	9.6 ± 0.1	9.9 ± 0.1	10.1 ± 0.3	0.19
MUFA (% energy)	12.0 ± 0.2	11.9 ± 0.2	12.5 ± 0.5	0.36
PUFA (% energy)	5.7 ± 0.1	5.6 ± 0.1	5.5 ± 0.2	0.46
Cholesterol (mg/d)	242.4 ± 7.3	235.1 ± 7.6	252.3 ± 15.9	0.58
Carbohydrates (% energy)	52.9 ± 0.5	53.0 ± 0.5	51.9 ± 1.0	0.60
Fiber (g/100 g carbohydrates)	9.2 ± 0.2	9.4 ± 0.2	9.3 ± 0.4	0.60
Protein (% energy)	16.9 ± 0.2	16.9 ± 0.2	16.9 ± 0.4	0.98
Alcohol (g/day)	6.9 ± 0.5	7.1 ± 0.6	7.9 ± 1.2	0.57

* Notes: Metabolic characteristics are adjusted for subject characteristics and dietary variables that were different between each genotype (ethnicity, age, gender, energy intake). Metabolic characteristics include: waist circumference, systolic and diastolic blood pressures, total, LDL and HDL cholesterol, triglycerides, free fatty acids, hs-CRP, glucose, insulin, HOMA-IR and HOMA-β.

** P values for differences between genotypes were obtained using one-way analysis of variance, and the Chi-square test was used to test for differences between genotypes in categorical variables. Median ± interquartile range given for hs-CRP.

a,b Different letters represent statistically significant differences between groups (P < 0.05).

Abbreviations: hs-CRP, high-sensitivity C-reactive protein; HOMA-IR, homeostasis model assessment of insulin resistance; HOMA-β, homeostasis model assessment of beta cell function; LDL, low-density lipoprotein; HDL, high-density lipoprotein; SFA, saturated fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids.

Figure 1 Interaction between dietary fat, the rs7801406 polymorphism, and HOMAIR levels.

Notes: Values are means ± standard error of the mean adjusted for total: HDL cholesterol ratio, plasma triglycerides, waist circumference, and ethnocultural group. Dietary fat was inversely related to HOMA-IR in A/A carriers (β = −0.012 ± 0.006, P = 0.047) and positively among G/G homozygotes (β = 0.005 ± 0.002, P = 0.03). This relationship (in the G/G carriers) was significantly different from the A/A homozygotes (P = 0.02).
Abbreviations: HDL, high-density lipoprotein; HOMA-IR, homeostasis model assessment of insulin resistance.