Which of the following anti-diabetic drugs can cause vitamin B12 deficiency? (AI 2012)
a. Meifonnin and phenformin are biguanides and are preferred agents for obese patients (as these cause weight loss).
b. These drugs decrease blood glucose by decreasing the production (inhibit gluconeogenesis and glycogenolysis) and increasing the utilization (stimulation of glycolysis and tissue uptake of glucose).
c. These drugs also inhibit the intestinal absorption of glucose.
d. Lactic acidosis (more with phenformin) and megaloblastic anemia (more with metformin) due to vitamin B12 deficiency are the major adverse effects of these drugs. Lactic acidosis is more likely to occur in the presence of hepatic and renal impairment or alcohol ingestion.
e. Other contra-indications include cardiac failure, and chronic hypoxic lung disease.
f. Metforrnin is also useful for polycystic ovarian disease (PCOD).
g. Metformin is the only oral agent that has been demonstrated to reduce macrovascular events in type 2 DM.