Which of the following is true of biguanides: September 2011
Ans. A: Cause little or no hypoglycemia Metformin does not lower blood sugar in normal subjects By itself, it does not produce hypoglycemia in diabetics. However it potentiates the hypoglycemic action of insulin and sulfonylureas Biguanide Examples of biguanides: - Metformin - widely used in treatment of diabetes mellitus type 2 - Phenformin - withdrawn from the market in most countries due to toxic effects - Buformin - withdrawn from the market due to toxic effects - Proguanil - an antimalarial drug Biguanides do not affect the output of insulin, unlike other hypoglycemic agents such as sulfonylureas and meglitinides. Therefore, not only are they effective in Type 2 diabetics but they can also be effective in Type 1 patients in conce with insulin therapy. The mechanism of action of biguanides is not fully understood. However, in hyperinsulinemia, biguanides can lower fasting levels of insulin in plasma. Their therapeutic uses derive from their tendency to reduce gluconeogenesis in the liver, and, as a result, reduce the level of glucose in the blood. Biguanides also tend to make the cells of the body more willing to absorb glucose already present in the blood stream, and there again reducing the level of glucose in the plasma. The most common side effect is diarrhea and dyspepsia, occurring in up to 30% of patients. The most impoant and serious side effect is lactic acidosis, therefore metformin is contraindicated in renal insufficiency. Renal functions should be assessed before staing metformin. Phenformin and buformin are more prone to cause acidosis than metformin; therefore they have been practically replaced by it. However, when metformin is combined with other drugs (combination therapy), hypoglycemia and other side effects are possible.
Cause little or no hypoglycemia
Stimulates pancreatic beta cells
Completely metabolized
Promotes hepatic gluconeogenesis