One of the reasons I avoid tap water here apart from the awful taste is that it is fluoridated and it can affect BG levels adversly.
In fact a friend was told by her consultant not to drink it as she had extremely high BG and was having great difficulty bringing it down.
"Clinical Study of Effect of High Fluoride on the Function of the Pancreas Islet B Cells
XIE, Yong-ping1, GE Xiang-jin2, JIANG Yu-4ng3, FENG Ming-ying1, FAN Ying-yi1, Wang Fu-lun1, WEI Zeng-fu1,
ZHAO Gui-lu3, QIN-Ai-qiong1
1Gaomi People’s Hospital, Shandong Province, Gaomi 261500, China
2Gaomi Epidemic Prevention Stations, Shandong Province, Gaomi 261500
3Gaomi Endemic Disease Prevention Office, Shandong, Gaomi 261500
Objective To study the effect of excessive fluoride intake on the function of pancreas islet’s B cells.
Methods: We performed x-rays, determined the [F] in the urine, conducted OGTT insulin and C-peptide releasing tests in
the serum, and analysed the drinking water quality of the exposed group and control group.
Results: (1) The [F] in drinking water and the geometrical mean of the [F] in the urine of the people of the exposed group
were higher than those of the control group. (2) The fastng blood glucose concentration and the peak value after oral
glucose in the exposed group were higher than those of the control group. The peak value was found later in the
exposed group than in the control group. (3) The detectable rate of Diabetes and IGT in the exposed group was higher
than that in the control group. (4) The blood-insulin and C-peptide in the exposed group were lower than in the control
group, although the peak value after oral glucose was found later in the exposed group.
Conclusions: Excessive fluoride can do much harm to the function of the pancreas islet B cells and the effects change with the degree of fluorosis."
link
http://www.fluoridealert.org/wp-content/uploads/xie-2000.pdf