These substances are not considered to be medications by the US FDA and are therefore not regulated as such. This means that there are no standards in place to ensure that a given product contains the substance or dose as described on the label. There are also no requirements to perform studies showing that the products are safe or effective. Side effects of supplements are typically not well understood, and some supplements can interfere with the action of medications.
Normally, blood glucose levels are tightly controlled by insulin, a hormone produced by the pancreas. Insulin lowers the blood glucose level. When the blood glucose elevates (for example, after eating food), insulin is released from the pancreas. This release of insulin promotes the uptake of glucose into body cells. In patients with diabetes, the absence of insufficient production of or lack of response to insulin causes hyperglycemia. Diabetes is a chronic medical condition, meaning that although it can be controlled, it lasts a lifetime.