Income and wealth inequality is associated with young-onset type 2 diabetes

Table 1 Characteristics of young adults aged 20-39 years in 2008 in Taiwan

Family income	Low income (n = 4089530)	Middle income (n = 2403286)	High income (n = 857452)	P value
Age groups (years)
20-26	1472366 (36.0)	581685 (24.2)	240454 (28.0)	< 0.001
27-33	1508413 (36.9)	1120116 (46.6)	211102 (24.6)	< 0.001
34-39	1108751 (27.1)	701485 (29.2)	405896 (47.3)	< 0.001
Age (years)	29.2 (5.6)	30.2 (5.1)	31.2 (6.1)	< 0.001
Sex				< 0.001
Male	2027489 (49.6)	1178843 (49.1)	484829 (56.5)
Female	2062041 (50.4)	1224443 (50.9)	372623 (43.5)
Family income, NTD per months
Income (NTD)	14642 (8104)	32302 (6690)	62268 (19043)	< 0.001
Comorbidity
Overweight	1909 (0)	1115 (0)	307 (0)	0.001
Obesity	7468 (0.2)	4571 (0.2)	1746 (0.2)	0.001
Severe obesity	1758 (0)	958 (0)	306 (0)	0.014
Smoking	23634 (0.6)	11889 (0.5)	3588 (0.4)	< 0.001
Alcohol	16724 (0.4)	3722 (0.2)	815 (0.1)	< 0.001
Hypertension	50019 (1.2)	31337 (1.3)	14360 (1.7)	< 0.001
Gout	63456 (1.6)	43384 (1.8)	19583 (2.3)	< 0.001
Psychotic disorders	85271 (2.1)	25667 (1.1)	8480 (1.0)	< 0.001
Charlson Comorbidity Index score	1.3 (0.8)	1.2 (0.7)	1.2 (0.6)	< 0.001
Frequency of outpatients visits per year	23 (24.2)	22.3 (21.3)	21.4 (20.6)	< 0.001
Follow-up (years)	8.0 (0.4)	8.0 (0.3)	8.0 (0.3)	< 0.001

The expression of data is mean (SD). The New Taiwan Dollar: United States Dollar ratio was 30:1 in 2009. NTD: New Taiwan Dollar.

Table 2 Risk of all-cause mortality and diabetes incidence among young adults aged 20-39 years in 2008 in Taiwan by family income group

Case		Incidence rate per 1000 person-years	Crude model		Adjusted model
			HR (95%CI)	P value	HR (95%CI)	P value
Diabetes incidence
Family income groups
Low income	109247	3.39	1.11 (1.10-1.13)	< 0.001	1.46 (1.44-1.48)	< 0.001
Middle income	58892	3.10	1.05 (1.04-1.07)	< 0.001	1.29 (1.27-1.31)	< 0.001
High income	19563	2.88	Ref.		Ref.
Diabetes incidence from hospitalization
Low income	17070	0.53	2.14 (2.03-2.25)	< 0.001	2.75 (2.62-2.90)	< 0.001
Middle income	6242	0.33	1.38 (1.31-1.46)	< 0.001	1.70 (1.61-1.80)	< 0.001
High income	1577	0.23	Ref.		Ref.
Diabetes incidence from emergency treatment
Low income	15626	0.48	2.10 (1.99-2.21)	< 0.001	2.71 (2.57-2.86)	< 0.001
Middle income	6098	0.32	1.41 (1.33-1.49)	< 0.001	1.73 (1.63-1.83)	< 0.001
High income	1534	0.23	Ref.		Ref.
Diabetes incidence from outpatients
Low income	92177	2.86	1.02 (1.01-1.04)	< 0.001	1.35 (1.33-1.37)	< 0.001
Middle income	52650	2.77	1.02 (1.01-1.04)	< 0.001	1.25 (1.23-1.27)	< 0.001
High income	17986	2.65	Ref.		Ref.
All-cause mortality
Low income	48909	1.50	2.40 (2.32-2.48)	< 0.001	2.79 (2.70-2.88)	< 0.001
Middle income	15131	0.79	1.36 (1.32-1.41)	< 0.001	1.59 (1.53-1.65)	< 0.001
High income	3872	0.57	Ref.		Ref.

Model adjusted for age, sex, overweight, obesity, severe obesity, smoking, alcohol, hypertension, dyslipidemia, gout, psychotic disorders, Charlson Comorbidity Index scores, and frequency of outpatient visits per year. HR: Hazard ratio; CI: Confidence interval; Ref.: Reference.