Metformin lipid metabolism effects

Patients with diabetes frequently have elevated plasma concentrations of triglycerides and low-density lipoprotein (LDL) cholesterol concentration, together with reduced high-density lipoprotein (HDL) cholesterol concentration. Studies of the effect of sulphonylureas on lipid metabolism in Type-II diabetes, however, are quite controversial and the results have been discussed widely during the last few years. Glibenclamide and metformin were found to have no primary effect on serum triglycerides (Rains et al., 1988). Neither drug altered HDL cholesterol or subfraction cholesterol. Metformin alone, however, reduced LDL cholesterol. 

Hollenbeck CB, Johnston P, Varasteh, BB, et al. Effects of metformin on glucose insulin and lipid metabolism in patients with mUd hypeitryglyceridaemia and noninsulin dependent diabetes by glucose tolerance test criteria. Diabete Metab 1991 17 483 89. 

Reaven GM. Effect of metformin on various aspects of glucose, insulin and lipid metabolism in patients with non-insulin-dependent diabetes mellitus with varying degrees of hyperglycemia. Diab/Metab Rev 1995 11 S97-S108. 

Metformin also has been shown to produce beneficial effects on serum lipid levels and thus has become a first-line agent for type 2 DM patients with metabolic syndrome. Triglyceride and low-density lipoprotein (LDL) cholesterol levels often are reduced by 8% to 15%, whereas high-density lipoprotein (HDL) cholesterol improves by approximately 2%. A modest weight loss of 2 to 3 kg (4.4—6.6 lb) also has been reported with metformin therapy. Metformin often is used in combination with a sulfonylurea or a thiazolidinedione for synergistic effects. 

Pharmacokinetics. Metformin has approximately 50% to 60% oral bioavailability, low lipid solubility, and a volume of distribution that approximates body water. Metformin is not metabolized and does not bind to plasma proteins. Metformin is eliminated by renal tubular secretion and glomerular filtration. The average half-life of metformin is 6 hours, though pharmacodynamically, metformin s an-tihyperglycemic effects last >24 hours. 

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