Relationship between urinary iodine concentration and all-cause mortality in individuals with diabetes: An analysis of National Health and Nutrition Examination Survey 2005 - 2018.

Abstract

Background: Urinary iodine concentration (UIC) is related to prediabetes and diabetes; nevertheless, there is still a dearth of data about the association of UIC with all-cause mortality in diabetics.

Objective: To investigate the connection between UIC and all-cause mortality in diabetics.

Methods: Data from NHANES, collected on adult Americans between 2005 and 2018, were used in this investigation. The associations between ln-transformed creatinine-adjusted UIC (urinary iodine/creatinine, UI/Cr) and all-cause mortality in diabetics, as well as in older diabetics with a history of thyroid disease, were analyzed using Cox proportional hazards models and survival curve analysis. Subgroup analyses and interaction tests were conducted to examine variables affecting the association between ln(UI/Cr) and all-cause mortality in people with diabetes. Lastly, the effect of smoking on this association was tested by using restricted cubic spline (RCS).

Results: A total of 2,141 participants were included in this study. ln(UI/Cr) was significantly associated with a higher risk of all-cause mortality in diabetics in the unadjusted model (HR= 1.38, 95% CI: 1.20 - 1.58, P<0.001), but this association lost significance when confounding variables were considered (P> 0.05). Subgroup analysis revealed that Mexican-Americans and females had a stronger positive connection (P<0.05) between ln(UI/Cr) and the risk of all-cause mortality among diabetics. There was a significant correlation between ln(UI/Cr) and mortality in female smokers with diabetes (95% CI: 1.16 - 2.18, P=0.004). The RCS analysis demonstrated a significant non-linear relationship (P-non-linear= 0.0131). ln(UI/Cr) was significantly and positively associated with all-cause mortality in elderly diabetic individuals with a history of thyroid disease (HR= 1.38, 95% CI: 1.01 - 1.87, P=0.042).

Conclusion: In American individuals with diabetes, our research validates the association between UI/Cr and all-cause mortality. This correlation might offer additional dietary suggestions for the management of individuals with diabetes.