Patients with Type 2 Diabetes
In the presence of normal kidney function, there are no differences between single- or multiple-dose (pharmacokinetics) bodily reactions to metformin between patients with type 2 diabetes and normal subjects nor is there any accumulation of metformin in either group at usual clinical doses.

Decreased Kidney Function
In patients with decreased kidney function, the time it takes for half of the levels of metformin to leave your body is prolonged and the excretion by the kidney is decreased in proportion to the decrease in creatinine clearance

Decreased Liver Function
No pharmacokinetic studies of metformin have been conducted in patients with decreased liver function

Geriatrics
Limited data from controlled pharmacokinetic studies of metformin in healthy elderly subjects suggest that total plasma clearance of metformin is decreased, the half-life is prolonged, and peak level in the blood is increased, compared to healthy young subjects.

From these data, it appears that the change in metformin pharmacokinetics with aging is primarily accounted for by a change in kidney function.

RIOMET (metformin hydrochloride oral solution) treatment should not be started in patient >= 80 years of age unless measurement of creatinine clearance demonstrates that kidney function is not reduced.

Pediatrics
The safety and effectiveness of metformin for the treatment of type-2 diabetes have been established in pediatric patient ages 10-16 years (studies have not been conducted in pediatric patients below the age of 10 years).

Gender
Metformin pharmacokinetic parameters did not differ significantly between normal subjects and patients with type 2 diabetes when analyzed according to gender.

Race
No studies of metformin pharmacokinetic parameters according to race have been performed. In controlled clinical studies of metformin in patients with type 2 diabetes, the elevated blood sugar lowering effect was comparable in whites (n= 249), blacks (n= 51), and Hispanics (n= 24).