Overall, 30,500 individuals were included in the analysis, of whom 19,600 (64.3%) were women. The mean age of participants was 41.6 ± 11.9 years. The mean BMI and WC were 27.6 ± 5.3 kg/m2 and 92.5 ± 13.4 cm, respectively. Overall, the majority were married (83.0%), urban residents (73.1%), had primary education (44.2%), and were never-smokers (89.1%). HTN and family history of diabetes were observed in 19.7% and 34.2%, respectively (Table 1).
Among all participants, 9,405 (30.8%) were identified to have prediabetes, and 4,646 (15.2%) had diabetes. Self-reported diabetes was among 2,694 (8.9%) individuals. The highest prevalence of diabetes and prediabetes was observed among people aged ≥ 50 years (32.2% and 33.0%) and those with BMI ≥ 30 kg/m2 (20.9% and 34.7%). Prevalence of diabetes was comparable in both sexes (15%), while it was higher among urban residents and marrieds (16.4% and 16.1%), the illiterates (24.6%), and those who had WC ≥ 90 cm (20.5%), and HTN (33.4%). Regarding prediabetes, the prevalence was slightly higher among men (32.0%) and urban residents (31.5%), and those who had WC ≥ 90 cm (33.2%) (Table 1).
Table 1. Characteristics of the Khuzestan Comprehensive Health Study (KCHS) participants.
Variable
|
|
Total number (%)
|
Prediabetes
|
Diabetes
|
Total
|
|
30500
|
9405
|
4646
|
Sex
|
Male
|
10898 (35.7 %)
|
3486 (32.0 %)
|
1655 (15.2 %)
|
|
Female
|
19600 (64.3 %)
|
5919 (30.2 %)
|
2991 (15.3 %)
|
Age (years)
|
|
|
|
|
20-35
|
10273 (33.7 %)
|
2767 (26.9 %)
|
347 (3.4 %)
|
|
35-49.9
|
11676 (38.4 %)
|
3815 (32.7 %)
|
1557 (13.3 %)
|
|
≥50
|
8492 (27.9 %)
|
2802 (33.0 %)
|
2735 (32.2 %)
|
BMI (Kg/m2)
|
|
|
|
|
<25
|
9829 (32.4 %)
|
2596 (26.4 %)
|
887 (9.0 %)
|
|
25-29.9
|
11440 (37.7 %)
|
3620 (31.6 %)
|
1824 (15.9 %)
|
|
≥30
|
9088 (29.9 %)
|
3152 (34.7 %)
|
1903 (20.9 %)
|
Waist circumference (cm)
|
|
|
|
|
<90
|
12405 (40.9 %)
|
3407 (27.5 %)
|
941 (7.6 %)
|
|
≥90
|
17953 (59.1 %)
|
5962 (33.2 %)
|
3673 (20.5 %)
|
Hypertension
|
No
|
24493 (80.3 %)
|
7507 (30.7 %)
|
2641 (10.8 %)
|
|
Yes
|
5993 (19.7 %)
|
1895 (31.6 %)
|
2004 (33.4 %)
|
Diabetes family history
|
No
|
20025 (65.8 %)
|
6186 (30.9 %)
|
2299 (11.5 %)
|
Yes
|
10418 (34.2 %)
|
3205 (30.8 %)
|
2338 (22.4 %)
|
Education
|
|
|
|
|
|
Illiterate
|
6606 (21.7 %)
|
1983 (30.0 %)
|
1626 (24.6 %)
|
|
Elementary
|
13480 (44.2 %)
|
4305 (31.9 %)
|
2072 (15.4 %)
|
|
Secondary
|
7844 (25.7 %)
|
2342 (29.9 %)
|
802 (10.2 %)
|
|
Higher education
|
2563 (8.4 %)
|
773 (30.2 %)
|
145 (5.7 %)
|
Cigarette smoking
|
|
|
|
|
|
Never
|
27046 (89.1 %)
|
8410 (31.1 %)
|
4061 (15.0 %)
|
|
Past
|
974 (3.2 %)
|
301 (30.9 %)
|
251 (25.8 %)
|
|
Current
|
2324 (7.7 %)
|
649 (27.9 %)
|
311 (13.4 %)
|
Marital status
|
Single
|
5178 (17.0 %)
|
1561 (30.2 %)
|
566 (10.9 %)
|
|
Married
|
25320 (83.0 %)
|
7844 (31.0 %)
|
4080 (16.1 %)
|
Residence
|
Urban
|
22284 (73.1 %)
|
7008 (31.5 %)
|
3656 (16.4 %)
|
|
Rural
|
8213 (26.9 %)
|
2397 (29.2 %)
|
990 (12.1 %)
|
Wealth index
|
|
|
|
|
|
Q1
|
25 %
|
2273 (29.8 %)
|
1126 (14.7 %)
|
|
Q2
|
25 %
|
2345 (31.2 %)
|
1151 (15.3 %)
|
|
Q3
|
25 %
|
2459 (30.4 %)
|
1190 (14.7 %)
|
|
Q4
|
25 %
|
2275 (32.2 %)
|
1147 (16.2 %)
|
Results on multivariate analysis of the factors associated with diabetes and prediabetes risk are demonstrated in Table 2. Compared to the participants aged under 35 years, those aged between 35-49.9 years [RR (95% CI); 5.02 (4.43, 5.69)] or ≥ 50 years [RR (95% CI); 18.54 (16.39, 20.98)] were more likely to be affected by diabetes. Moreover, compared to the participants with BMI < 25 kg/m2, those who had BMI 25-29.9 kg/m2 [RR (95% CI); 2.06 (1.88, 2.25)] or BMI ≥ 30 kg/m2 [RR (95% CI); 3.17 (2.89, 3.47)] were more likely to be affected by diabetes. HTN [RR (95%CI); 5.1 (4.7, 5.4)], WC ≥ 90 cm [RR (95% CI); 3.6 (3.3, 3.9)], and history of diabetes in first-degree family member [RR (95% CI); 2.4 (2.2, 2.6)] were also found to be significantly associated with diabetes. Furthermore, higher education was associated with the lowest risk of diabetes [RR (95% CI); 0.10 (0.08, 0.12)] (Table 2).
Regarding the factors associated with prediabetes, results showed that compared to the participants aged under 35 years, those aged between 35-49.9 [RR (95% CI); 1.57 (1.48, 1.67)] or ≥ 50 years [RR (95% CI); 2.44 (2.27, 2.61)] were more likely to be affected by prediabetes. Similarly, compared to the participants with BMI < 25 kg/m2, those who had BMI 25-29.9 kg/m2 [RR (95% CI); 1.44 (1.36, 1.54)] or BMI ≥ 30 kg/m2 [RR (95% CI); 1.86 (1.74, 1.99)] were more likely to be affected by prediabetes. HTN [RR (95%CI); 1.71 (1.60,1.83)], WC ≥ 90 cm [RR (95% CI); 1.67 (1.59, 1.77)], and having a first-degree relative with diabetes [RR (95% CI); 1.22 (1.15, 1.29)] were significantly associated with prediabetes. Similar to diabetes, the highest educational degree was also associated with the lowest risk of prediabetes [RR (95% CI); 0.58 (0.51, 0.64)]. Furthermore, female sex was slightly protective against prediabetes [(RR (95% CI); 0.88 (0.83, 0.93)] (Table 2).
Table 2. Univariate and multivariate analysis of risk factors associated with diabetes and prediabetes in the Khuzestan study.
Variables
|
Prediabetes
|
Diabetes
|
Unadjusted. RR
(95% CI)
|
Adjusted. RR*
(95% CI)
|
Unadjusted. RR
(95% CI)
|
Adjusted. RR*
(95% CI)
|
Sex
|
Male
|
|
|
|
|
|
Female
|
0.91 (0.87, 0.96)
|
0.88 (0.83, 0.93)
|
0.97 (0.91, 1.04)
|
1.01 (0.94, 1.09)
|
Age (years)
|
<35
|
|
|
|
|
|
35-49.9
|
1.57 (1.48, 1.66)
|
1.57 (1.48, 1.67)
|
5.1 (4.51, 5.75)
|
5.02 (4.43, 5.69)
|
|
≥50
|
2.45 (2.29, 2.63)
|
2.44 (2.27, 2.61)
|
19.1 (16.94, 21.52)
|
18.54 (16.39, 20.98)
|
BMI (Kg/m2)
|
<25
|
|
|
|
|
|
25-29.9
|
1.48 (1.39, 1.57)
|
1.44 (1.36, 1.54)
|
2.18 (1.99, 2.38)
|
2.06 (1.88, 2.25)
|
|
≥30
|
1.91 (1.79, 2.04)
|
1.86 (1.74, 1.99)
|
3.38 (3.09, 3.69)
|
3.17 (2.89, 3.47)
|
Waist circumference (cm)
|
<90
|
|
|
|
|
|
≥90
|
1.70 (1.61, 1.79)
|
1.67 (1.59, 1.77)
|
3.78 (3.50, 4.09)
|
3.61 (3.33, 3.91)
|
Hypertension
|
No
|
|
|
|
|
|
Yes
|
1.73 (1.62, 1.85)
|
1.71 (1.60, 1.83)
|
5.20 (4.83, 5.6)
|
5.05 (4.68, 5.44)
|
Diabetes family history
|
No
|
|
|
|
|
Yes
|
1.23 (1.16, 1.29)
|
1.22 (1.15, 1.29)
|
2.41 (2.25, 2.57)
|
2.38 (2.22, 2.55)
|
Education
|
Illiterate
|
|
|
|
|
|
Elementary
|
0.92 (0.86, 0.98)
|
0.85 (0.79, 0.91)
|
0.54 (0.50, 0.58)
|
0.43 (0.40, 0.47)
|
|
Secondary
|
0.75 (0.70, 0.81)
|
0.65 (0.59, 0.70)
|
0.31 (0.29, 0.35)
|
0.21 (0.19, 0.23)
|
|
Higher education
|
0.71 (0.64, 0.79)
|
0.58 (0.51, 0.64)
|
0.16 (0.14, 0.19)
|
0.10 (0.08, 0.12)
|
*Data are adjusted for smoking (never vs. ever), marital status (single vs. married), residence (urban vs. rural), and wealth index.
*RR: Relative risk
We further evaluated the characteristics of the normal weight and underweight participants affected by diabetes (Table 3). Overall, 887 participants (50.2% female) with BMI < 25 kg/m2 were identified to have diabetes. The mean WC in this group was 86.1 ± 8.8 cm, and the majority had a WC < 90 cm (63%). The mean age of these participants was 50.5 ± 10.7 years, and the majority aged ≥ 50 years (61.4%), were married (85.7%) and were urban residents (71.8%). Most of these individuals had no history of HTN (64%) and smoking (82.1%), while nearly half had a family history of diabetes (48.2%). (Table 3).
Table 3. Characteristics of the Khuzestan study participants with diabetes who had Body Mass Index (BMI) < 25 kg/m2
Variable
|
|
Number (%)
|
Sex
|
Male
|
442 (49.8 %)
|
|
Female
|
445 (50.2 %)
|
Age (years)
|
|
|
<35
|
96 (10.8 %)
|
|
35-49.9
|
246 (27.8 %)
|
|
≥50
|
544 (61.4 %)
|
Waist circumference (cm)
|
|
|
<90
|
557 (62.8 %)
|
|
≥90
|
330 (37.2 %)
|
Hypertension
|
No
|
568 (64.0 %)
|
|
Yes
|
319 (36.0 %)
|
Diabetes
family history
|
No
|
459 (51.8 %)
|
Yes
|
427 (48.2 %)
|
Education
|
|
|
|
Illiterate
|
309 (34.9 %)
|
|
Elementary
|
393 (44.4 %)
|
|
Secondary
|
160 (18.1 %)
|
|
Higher education
|
24 (2.7 %)
|
Smoking
|
|
|
|
Never
|
725 (82.1 %)
|
|
Ever
|
158 (17.9 %)
|
Marital Status
|
Single
|
127 (14.3 %)
|
|
Married
|
760 (85.7 %)
|
Residence
|
Urban
|
637 (71.8 %)
|
|
Rural
|
250 (28.2 %)
|