Both youth and long-term vitamin D status is associated with risk of type 2 diabetes mellitus in adulthood: a cohort study

Figures & data

Table 1. Participants’ youth (in 1980) and adulthood characteristics by NFG, IFG and T2DM status in adulthood.

	NFG (n = 1733)	IFG^a (n = 473)	T2DM (n = 94)
Youth
Age (years)	10.1 (5.0)	11.4 (4.8)	13.1 (4.8)
Female, n (%)	1012 (58)	150 (32)	47 (50)
BMI (kg/m^2)	17.6 (3.0)	18.1 (3.0)	20.4 (4.0)
25OHD (nmol/L)	52.0 (15.2)	51.9 (15.6)	45.8 (14.2)
Study month, n (%)
September	104 (6)	29 (6)	7 (8)
October	1014 (59)	295 (62)	65 (69)
November	562 (32)	136 (29)	20 (21)
December	53 (3)	13 (3)	2 (2)
Physical activity index (z-score)	−0.02 (0.99)	0.15 (1.04)	−0.03 (0.93)
Systolic blood pressure (mmHg)	112 (12)	114 (12)	118 (14)
Fasting insulin (mU/L)	9.2 (5.7)	10.0 (5.8)	12.4 (6.4)
Triglycerides (mmol/L)	0.66 (0.30)	0.66 (0.29)	0.79 (0.46)
HDL-C (mmol/L)	1.57 (0.31)	1.55 (0.30)	1.49 (0.31)
Parental history of diabetes, n (%)	33 (2)	10 (2)	6 (6)
Fruit consumption (>6 times/week), n (%)	1404 (81)	381 (81)	65 (69)
Vegetable consumption (>6 times/week), n (%)	591 (34)	159 (34)	29 (31)
Smokers, n (%)	85 (5)	36 (8)	13 (14)
Parental years attended at school	10.0 (3.3)	9.9 (2.9)	9.1 (3.1)
Adulthood^b
Age (years)	41.1 (5.0)	42.4 (4.8)	44.1 (4.8)
BMI (kg/m^2)	25.5 (4.6)	28.0 (4.7)	32.2 (6.1)
25OHD (nmol/L)	56.3 (19.8)	55.1 (18.1)	49.0 (16.8)
Physical activity index	9.1 (1.9)	8.7 (1.8)	8.4 (1.6)
Smokers, n (%)	299 (17)	111 (24)	22 (29)
Educational status
Grammar school	225 (14)	68 (16)	16 (20)
College or vocational school	717 (46)	212 (49)	42 (53)
University degree	616 (40)	149 (35)	22 (27)
Fasting glucose (mmol/L)	5.08 (0.34)	5.96 (0.28)	7.06 (2.39)
Fasting insulin (mU/L)	7.9 (8.5)	12.4 (10.5)	21.8 (21.1)
Fruit consumption (g/day)	196 (207)	175 (190)	194 (164)
Vegetable consumption (g/day)	274 (187)	261 (187)	298 (180)
Mean 25OHD (nmol/L)^c	54.2 (13.8)	53.5 (12.9)	47.4 (12.8)

NFG: normal fasting glucose; IFG: impaired fasting glucose; T2DM: type 2 diabetes mellitus; BMI: body mass index; 25OHD: 25-hydroxyvitamin D; HDL-C: high-density lipoprotein cholesterol.

a IFG cut-off is 5.6 mmol/L.

b All variables used data from the latest available values in adulthood (from 2001, 2007 and 2011), and the number of participants are 1767 for fruit and vegetable consumption and ranged from 2067 to 2300 for other variables.

c See “Statistical analyses” section in the text for how this was calculated.

Data are mean (SD) for continuous variable and number (%) for categorical variables.

Table 2. The association between continuous youth and the mean of youth and adulthood 25OHD levels, T2DM and IFG in adulthood.

		Childhood serum 25OHD levels	Mean of childhood and adulthoodserum 25OHD levels
	n	Odds ratio (95% CI)^a	Odds ratio (95% CI)^b
Model 1
NFG	1733	Reference	Reference
IFG	473	1.00 (0.89–1.10)	0.95 (0.86–1.06)
T2DM	94	0.64 (0.51–0.81)	0.57 (0.45–0.72)
Model 2
NFG	1733	Reference	Reference
IFG	473	1.05 (0.93–1.18)	1.00 (0.90–1.12)
T2DM	94	0.71 (0.55–0.91)	0.63 (0.50–0.81)
Model 3
NFG	1733	Reference	Reference
IFG	473	1.04 (0.93–1.18)	1.00 (0.89–1.12)
T2DM	94	0.73 (0.57–0.95)	0.65 (0.51–0.84)
Model 4
NFG	1733	Reference	Reference
IFG	473	1.05 (0.93–1.19)	1.06 (0.94–1.19)
T2DM	94	0.74 (0.56–0.97)	0.73 (0.56–0.95)

NFG: normal fasting glucose; IFG: impaired fasting glucose (cut-off 5.6 mmol/L); T2DM: type 2 diabetes mellitus; 25OHD: 25-hydroxyvitamin D.

a Odds ratio for every SD (15.2 nmol/L) increase in childhood serum 25OHD levels.

b Odds ratio for every SD (13.6 nmol/L) increase in the mean of childhood and adulthood serum 25OHD levels. Missing data of adult 25OHD were imputed for 119 participants.

Bold values denote statistical significance, p < .05.

Model 1: unadjusted; Model 2: adjusted for age, sex, body mass index, month of blood taken, parental history of diabetes and fruit consumption; Model 3: model 2 + physical activity, smoking, systolic blood pressure, high-density lipoprotein cholesterol, triglycerides, insulin, vegetable consumption, socioeconomic status (the parental length of time spent in education). Model 4: model 3 + adult body mass index (missing data of adult body mass index were imputed for 25 participants).

Table 3. Odds ratio of T2DM and IFG in adulthood by quarters of youth 25OHD levels.

	Quartile 1 (n= 587)	Quartile 2 (n= 602)	Quartile 3 (n= 565)	Quartile 4 (n= 546)	p for trend
25OHD, mean (range) (nmol/L)	33 (12–41)	46 (42–51)	57 (52–62)	72 (63–122)	–
NFG, n (%)^a	432 (73.6)	453 (75.2)	428 (75.8)	420 (76.9)	–
IFG, n (%)	116 (19.8)	125 (20.8)	120 (21.2)	112 (20.5)	–
Model 1	Reference	1.03 (0.77–1.37)	1.04 (0.78–1.39)	0.99 (0.74–1.33)	.99
Model 2	Reference	1.08 (0.80–1.46)	1.11 (0.81–1.51)	1.16 (0.83–1.60)	.39
Model 3	Reference	1.09 (0.80–1.47)	1.11 (0.81–1.53)	1.15 (0.83–1.61)	.40
Model 4	Reference	1.10 (0.81–1.50)	1.11 (0.81–1.54)	1.18 (0.84–1.66)	.37
T2DM, n (%)	39 (6.6)	24 (4.0)	17 (3.0)	14 (2.6)	–
Model 1	Reference	0.59 (0.35–0.99)	0.44 (0.25–0.79)	0.37 (0.20–0.69)	<.001
Model 2	Reference	0.71 (0.41–1.24)	0.54 (0.29–1.01)^b	0.49 (0.25–0.97)	.02
Model 3	Reference	0.73 (0.42–1.28)	0.58 (0.31–1.11)^b	0.52 (0.26–1.04)^b	.04
Model 4	Reference	0.78 (0.44–1.38)	0.62 (0.32–1.21)	0.54 (0.26–1.11)^b	.07

Values are odds ratio (95% confidence interval) unless otherwise stated.

NFG: normal fasting glucose; IFG: impaired fasting glucose (cut-off 5.6 mmol/L); T2DM: type 2 diabetes mellitus; 25OHD: 25-hydroxyvitamin D.

a Reference group for the outcome comparison.

b p < .1. Bold values denote statistical significance, p < .05.

Model 1: unadjusted; Model 2: adjusted for age, sex, body mass index, month of blood taken, parental history of diabetes and fruit consumption; Model 3: model 2 + physical activity, smoking, systolic blood pressure, high-density lipoprotein cholesterol, triglycerides, insulin, vegetable consumption, socioeconomic status (the parental length of time spent in education). Model 4: model 3 + adult body mass index (missing data of adult body mass index were imputed for 25 participants).

Table 4. Odds ratio of T2DM and IFG in adulthood by quarters of the mean of youth and adulthood 25OHD levels.

	Quartile 1 (n= 574)	Quartile 2 (n= 548)	Quartile 3 (n= 598)	Quartile 4 (n= 580)	p for trend
25OHD, mean (range) (nmol/L)	39 (15–44)	48.5 (44.5–52.4)	56.5 (52.5–62)	69 (62.5–124)	–
NFG, n (%)^a	413 (72.0)	418 (76.3)	452 (75.6)	450 (77.6)	–
IFG, n (%)	120 (20.9)	104 (19.0)	133 (22.2)	116 (20.0)	–
Model 1	Reference	0.86 (0.64–1.15)	1.01 (0.76–1.34)	0.89 (0.67–1.18)	.68
Model 2	Reference	0.88 (0.65–1.20)	1.00 (0.75–1.34)	1.01 (0.75–1.37)	.75
Model 3	Reference	0.87 (0.64–1.19)	1.00 (0.75–1.35)	1.00 (0.74–1.36)	.78
Model 4	Reference	0.91 (0.66–1.25)	1.09 (0.80–1.48)	1.14 (0.83–1.57)	.26
T2DM, n (%)	41 (7.1)	26 (4.7)	13 (2.2)	14 (2.4)	–
Model 1	Reference	0.63 (0.38–1.04)^b	0.29 (0.15–0.55)	0.31 (0.17–0.58)	<.001
Model 2	Reference	0.69 (0.41–1.18)	0.33 (0.17–0.64)	0.41 (0.21–0.77)	<.001
Model 3	Reference	0.70 (0.41–1.20)	0.35 (0.18–0.69)	0.43 (0.22–0.82)	.001
Model 4	Reference	0.80 (0.46–1.40)	0.41 (0.20–0.81)	0.55 (0.28–1.09)^b	.02

NFG: normal fasting glucose; T2DM: type 2 diabetes mellitus; IFG: impaired fasting glucose (cut-off 5.6 mmol/L); 25OHD: 25-hydroxyvitamin D.

Values are odds ratio (95% confidence interval) unless otherwise stated. Missing data of adult 25OHD were imputed for 119 participants.

a Reference group for the outcome comparison.

b p < 0.1. Bold values denote statistical significance, p < .05.

Model 1: unadjusted; Model 2: adjusted for age, sex, body mass index, month of blood taken, parental history of diabetes and fruit consumption; Model 3: model 2 + physical activity, smoking, systolic blood pressure, high-density lipoprotein cholesterol, triglycerides, insulin, vegetable consumption, socioeconomic status (the parental length of time spent in education). Model 4: model 3 + adult body mass index (missing data of adult body mass index were imputed for 25 participants).