Association of BMI and fasting insulin with cardiovascular disease risk factors in seven-year-old Icelandic children

Figures & data

Table I.  Descriptive statistics of the study population.

	All		Girls		Boys
	Sample size	Mean (SD)	n	Mean (SD)	n	Mean (SD)	p	95% CI
Age (years)	267	7.3 (0.3)	148	7.3 (0.3)	119	7.2 (0.3)	0.3	−0.01, 0.14
Height (cm)	267	127 (5.2)	148	126.4 (5.6)	119	127.8 (4.7)	0.04	0.12, 2.63
Weight (kg)	267	26.3 (4.4)	148	25.9 (4.5)	119	26.8 (4.2)	0.1	−0.14, 1.96
BMI (kg/m^2)	267	16.2 (1.9)	148	16.1 (1.9)	119	16.3 (1.9)	0.32	−0.22, 0.70
Sum of four skinfolds (mm)	223	27.0 (10.5)	125	28.7 (11)	98	24.7 (9.4)	0.005	1.23, 6.72
Total cholesterol (mmol/L)	164	4.4 (0.7)	88	4.4 (0.6)	76	4.3 (0.7)	0.16	−0.06, 0.34
HDL cholesterol (mmol/L)	164	1.55 (0.3)	88	1.5 (0.3)	76	1.6 (0.3)	0.25	−0.04, 0.14
LDL cholesterol (mmol/L)	164	2.5 (0.6)	88	2.6 (0.5)	76	2.5 (0.6)	0.09	−0.02, 0.32
Triglycerides (mmol/L)	164	0.64 (0.22)	88	0.7 (0.2)	76	0.6 (0.2)	0.003	0.03, 0.17
Fasting glucose (mmol/L)	152	4.6 (0.3)	84	4.6 (0.3)	68	4.7 (0.3)	0.35	−0.05, 0.15
HbA1C (%)	164	5.42 (0.26)	88	5.4 (0.4)	76	5.4 (0.3)	0.86	−0.12, 0.10
S. insulin (mU/L)	164	3.89 (2.05)	88	4.25 (2.11)	76	3.44 (1.91)	0.12	0.19, 1.44
SBP (mmHg)	220	94 (6)	125	94 (7)	97	95 (6)	0.29	−0.8, 2.6
DBP (mmHg)	220	56 (5)	125	55 (5)	97	57 (4)	0.04	0.1, 2.6

Notes: P-values and 95% confidence intervals are shown for the mean difference between boys and girls calculated with an unpaired t-test. BMI: body mass index; HDL: high-density lipoprotein; LDL: low-density lipoprotein; HbA1C: haemoglobin A1C; SBP: systolic blood pressure; DBP: diastolic blood pressure.

Table II.  Comparison of various cardiovascular risk factors between normal-weight and overweight children.

	Normal weight		Overweight
	Sample size	Mean (SD)	Sample size	Mean (SD)	p	95% CI
BMI	230	15.6 (1.2)	37	19.6 (1.6)	<0.001	3.4, 4.5
Total cholesterol (mmol/L)	142	4.4 (0.7)	22	4 (0.5)	0.004	0.14, 0.72
HDL cholesterol (mmol/L)	142	1.6 (0.3)	22	1.4 (0.3)	0.005	0.05, 0.32
LDL cholesterol (mmol/L)	142	2.6 (0.6)	22	2.3 (0.4)	0.046	0.00, 0.51
Triglycerides (mmol/L)	142	0.6 (0.2)	22	0.7 (0.3)	0.393	−0.15, 0.06
Fasting glucose (mmol/L)	132	4.6 (0.3)	20	4.8 (0.3)	0.007	0.06, 0.35
S. insulin (mU/L)	142	3.9 (2.4)	22	6 (3.8)	<0.001	0.91, 3.34
SBP (mmHg)	190	93.7 (6.5)	30	96.8 (5.1)	0.018	0.68, 5.59
DBP (mmHg)	190	55.6 (4.8)	30	57.5 (4.1)	0.034	1.03, 5.23

Notes: P-values and 95% confidence intervals are shown for the mean difference between normal weight and overweight children calculated with an independent t-test. 95% confidence interval shows the estimated interval where population average may lie. BMI: body mass index; HDL: high-density lipoprotein; LDL: low-density lipoprotein; HbA1C: haemoglobin A1C; SBP: systolic blood pressure; DBP: diastolic blood pressure.

Table III.  Comparison of estimated coefficients that associate BMI from simple linear regression and multiple linear regression best model.

	Simple linear regression			R-squared = 0.26Multiple linear regression*
	Beta	p	95% CI	Beta	p	95% CI
S. insulin (mU/L)	0.36	<0.001	0.22,0.50	0.23	0.004	0.07, 0.40
SBP (mmHg)	0.08	0.001	0.04,0.11	0.08	0.001	0.03, 0.13
HDL cholesterol (mmol/L)	−1.92	<0.001	−2.92, −0.93	−1.29	0.01	−2.30, −0.29
Fasting glucose (mmol/L)	1.42	0.005	0.43, 2.40	1.24	0.049	0.10, 2.28

Notes: Beta of 1.42 for fasting glucose means that increasing fasting glucose by one unit (for example from 4.5 mmol/L to 5.5 mmol/L) will on average increase BMI by 1.42 kg/m². The same applies for other coefficients. *Best and most parsimonious model was selected using AIC (Akaike information criterion) selection criteria. S. insulin: serum insulin; SBP: systolic blood pressure; HDL: high-density lipoprotein.

Table IV.  Comparison of estimated coefficients that associate serum insulin from simple linear regression and multiple linear regression best model.

	Simple linear regression			R-squared = 0.44Multiple linear regression*
	Beta	p	95% CI	Beta	p	95% CI
Sum of 4 SKF (mm)	0.09	<0.001	0.06, 0.12	0.05	0.001	0.02, 0.08
Triglycerides (mmol/L)	3.26	<0.001	1.92, 2.71	2.29	<0.001	1.13, 3.45
LDL (mmol/L)	−0.63	0.032	−1.21, −0.05	−0.71	0.003	−1.17, −0.25
Glucose (mmol/L)	2.58	<0.001	1.61, 3.54	2.81	<0.001	1.88, 3.73
Sex (0=girl, 1=boy)	−0.82	0.012	−1.45, −0.18	−0.62	0.02	−1.17, −0.08

Notes: Beta of 3.26 for triglycerides means that increasing triglycerides by one unit (for example from 0.5 mmol/L to 1.5 mmol/L) will on average increase serum insulin by 3.26 mU/L in univariate analysis. The same applies to other coefficients. *Best and most parsimonious model was selected using AIC (Akaike information criterion) selection criteria. S. insulin: serum insulin; LDL: low-density lipoprotein; SKF: skinfolds.