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New research from the West Virginia University School of Medicine has confirmed other research finding that Bisphenol A (BPA) – found among various plastics and resins in consumer goods – may lead or contribute to type 2 diabetes.
The researchers examined 3,516 people using the National Health and Nutritional Examination Survey of 2003-2008. The researchers compared the urinary BPA levels with fasting glucose levels to determine if there was a relationship between higher BPA concentration in the body and a prediabetic condition.
The researchers used the range for fasting glucose of 100-125 mg/dL and two-hour glucose levels of 140-199 mg/dL or a glycated hemoglobin (A1C) value of 5.7-6.4 % as the standard for a prediabetic condition. A normal A1C range is between 4% and 6%, and the lower the level, the better.
The researchers found that those subjects with BPA levels in the highest third (tertile) range of BPA concentration in the urine had an average of 34% increased incidence of prediabetic condition in terms of their glucose or A1C levels.
The researchers eliminated other possible known factors in diabetes such as weight, blood pressure, cholesterol levels, and alcohol consumption.
In their conclusion the researchers stated: "Higher urinary BPA levels are found to be associated with prediabetes independent of traditional diabetes risk factors."
The reality of this association has been strengthened not only by other human research, but also animal and laboratory studies.
For example, researchers from Korea's Keimyung University studied 1,210 Korean adults between 40 and 69 years old. This study crossed demographics and utilized medical records to confirm type 2 diabetic condition. The subjects were surveyed through questionaire, and their urine was tested for BPA concentration.
The study found that the average BPA concentration in the urine for the healthy adults was 2.03 ng/mL (nanograms per milliliter), while the average BPA concentration among the type 2 diabetic adults was 2.40 ng/mL. This is a difference of over 18%. A significant difference.
Several animal studies have found the same correlation. Studies from France and China have both linked BPA with diabetes. The French study and others in fact have found BPA linked with type 1 diabetes as well.
Laboratory studies have shown that at least one of the mechanisms of BPA relates to a derangement among the cells of the pancreas - which produce insulin. BPA has been found to speed up the formation of amyloid proteins secreted by beta-cells of the pancreas. The human islet amyloid polypeptide or hIAPP secretion is speeded up in the presence of BPA, found researchers from China's Huazhong University of Science and Technology.
hIAPP secretion speeds up the early death of the pancreas beta cells. This is because it will destroy the beta cells' membrane integrity.
This research and others has found that BPA also increases oxidation among the beta cells, which heightens their early death.
This was also found in research from Southern University and A&M College. Here the researchers found that the phenoxyl radicals from BPA were more toxic to cells than radicals from similar phenols. The researchers stated that this meant that the BPA-related oxidative stress factors lead to "higher risk of cardiovascular diseases, diabetes and abnormalities in hepatic enzymes."
Meanwhile, researchers from China's Tongji Medical College also found that BPA produced swelling among the mitochondria of pancreatic beta cells. This "impaired mitochondrial function" among the beta-cells was found related to an altered secretion of insulin among the cells.
Bisphenol A (BPA), found in larger concentration in polycarbonate plastics and epoxy resins, is most known for its endocrine disruption. Other studies have found BPA concentrations in more than 90% of urine samples of all ages, as well as umbilical cord blood.
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