Perhaps the most important, yet most overlooked, risk from excessive ingestion of fluoride toothpaste, is the impact it can have on blood glucose and insulin levels. In the 1980s, researchers at the University of Indiana reported that rats receiving acute, but relatively small, doses (0.5 mg/kg) of fluoride, had significantly higher glucose levels in their blood, and decreased levels of insulin. (Shahed 1986; Whitford 1987b).
Since that time, numerous studies have repeated this finding (in both animals and humans) at doses which many children routinely ingest from fluoride toothpaste. It is now estimated, for example, that blood fluoride levels of just 95 ppb produce an increase in glucose levels and a decrease in insulin. (Menoyo 2005). Strikingly, this level is routinely exceeded by about 5 to 10% of children using fluoride toothpaste (particularly those living in fluoridated communities).
This finding raises the obvious question of whether the widespread use and ingestion of fluoride toothpaste is contributing to, or exacerbating, the rising prevalence of diabetes in children.
Diabetes is a condition caused by persistently high glucose levels. A chemical that can simultaneously increase glucose levels and decrease insulin (insulin is a hormone that helps clear glucose from the blood) should be handled very carefully, particularly among those who already have diabetes. Indeed, several researchers have already begun suggesting that diabetic children should use toothpastes with low-fluoride content.