Fluoride Action Network


A cross-sectional study was performed to investigate the relationships between serum fluoride levels, glucose levels, and insulin secretion in a general population. A total of 330 healthy subjects (167 men; 163 women) aged between 40 and 69 years were examined. Lifestyle information was obtained using questionnaires. Blood samples were collected in the early morning, and biochemical parameters and glucose indices were measured. Serum ionic fluoride (SIF) levels were assessed using a highly sensitive method. Relationships between glucose indices and SIF levels were investigated using a multiple linear regression analysis. SIF levels positively correlated with fasting plasma glucose (FPG) and glycohemoglobin (HbA1c) levels in both sexes. In women, SIF levels negatively correlated with homeostasis model assessment insulin secretion (HOMA-B) levels. In men, the proportion of regular drinkers negatively correlated with HOMA-B, but not SIF levels. Although SIF levels < 1 umol/L were associated with reduced insulin secretion and increased FPG levels, the risk of diabetes was not elevated. These results suggest that increased SIF levels caused by a large fluoride intake and compromised renal function combined with poor lifestyle choices elevate the risk of diabetes. Further studies are warranted to elucidate the effects of fluoride on glucose metabolism.

*Original abstract online at https://link.springer.com/article/10.1007%2Fs12011-020-02415-1



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Author information



Itai K made a substantial contribution to the design of the study, performed the analysis, and drafted the manuscript. Okayama A designed the study and interpreted the results obtained. Onoda T, Nohara M, and Kuribayashi T made a substantial contribution to the design of the study and contributed to the analysis and interpretation of the results obtained. Ohsawa M, Tanno K, and Mori M contributed to the analysis and interpretation of the results obtained. All of the authors have revised the manuscript for important intellectual content and approved the final written manuscript.

Corresponding author

Correspondence to Kazuyoshi Itai.

*Original abstract online at https://link.springer.com/article/10.1007%2Fs12011-020-02415-1