The association between the dietary salt intake and glucose intolerance in healthy populations: from the Korean National Health and Nutritional Examination Survey (KNHANES)

Abstract Background Diabetes is known to be a strong risk factor for cardiovascular disease (CVD), and controlling salt intake in patients with type 2 diabetes may be a strategy to reduce the risk of CVD. However, the clear interaction between salt intake and glucose homeostasis has yet to be investigated. Our study evaluated the frequency and risk of glucose intolerance (pre-diabetes) according to dietary salt intake in a healthy population in Korea. Methods The Korean National Health and Nutritional Examination Survey (KNHANES) database was utilized for this study (https://knhanes.cdc.go.kr). A total of 72,751 subjects were enrolled in the KNHANES database from 2010 to 2018. The subjects were categorized into the following: normal fasting glucose (i.e., no pre-diabetes; FPG < 100 mg/dL), stage 1 pre-diabetes (FPG 100–109 mg/dL), stage 2 pre-diabetes (FPG 110–125 mg/dL). All subjects were divided into 8-equal groups according to their sodium intake: Group 1: ≤ 3.5 g, Group 2: 3.5 to 5.0 g, Group 3: 5.0 to 6.3 g, Group 4: 6.3 to 7.8 g, Group 5: 7.8 to 9.5 g, Group 6: 9.5 to 11.8 g, Group 7: 11.8 to 15.5 g, Group 8: > 15.5 g. This study is a retrospective cross-sectional study, so future risks cannot be assessed, but only the disease status assessment at the same time. Results Of the total 36,782 healthy adults, 17.6% (6,481 subjects) were pre-diabetic, of which 14.7% (5,397 subjects) were stage I pre-diabetic, and 2.9% (1,084 patients) were stage II pre-diabetic. From the lowest salt intake group (group 1, salt intake <3.5g) to the highest salt intake group (group 8, salt intake>.5g), the pre-diabetes prevalence continuously increased from 9.2% to 22.8%. The range of stage 1 pre-diabetes was 7.3% to 18.3%, and stage 2 diabetes was 1.9% to 4.5%. The odds ratio (OR) of pre-diabetic risk according to salt intake in the non-diabetic population, compared with group 1, group 2 was 1.46 (95% confidence interval [CI]: 1.30-1.68), group 3 was 1.84 (95% CI: 1.62 -2.08), group 4 was 2.24 (95% CI: 1.99-2.54), group 5 was 2.43 (95% CI: 2.15-2.75), group 6 was 2.49 (95% CI: 2.20-2.81), group 7 was 2.83 (95% CI: 2.51-3.19), group 8 was 2.90 (95% CI: 2.57-3.27). Conclusions High salt intake is significantly associated with pre-diabetes prevalence in healthy Korean population.