Some evidence for improved metabolic control in type 1 diabetes in adolescents with addition of metformin to insulin therapy

Clinical question: 
How effective is metformin added to insulin therapy in the management of type 1 diabetes mellitus in adolescents?
Bottom line: 
There is some evidence suggesting improvement of metabolic control on addition of metformin to insulin therapy for adolescents with poorly controlled type 1 diabetes who have insulin resistance. The combined therapy lowered HbA1c levels more than insulin plus placebo but did not improve insulin sensitivity, body weight or serum lipids. One study showed insulin dosage decreased by 10%. Side effects were mainly gastrointestinal upset (both studies reviewed) and hypoglycaemia (1 study).
Caveat: 
Only 2 trials, involving 3 months of treatment, could be included. Meta-analysis was not possible due to the clinical and methodological heterogeneity of data. No data on health-related quality of life, all-cause mortality or morbidity are currently available.
Context: 
Metabolic control, as measured by HbA1c, often deteriorates during puberty in young people with type 1 diabetes, possibly due to the development of insulin resistance. This creates a great need for alternative therapeutic strategies for these patients.
Review CD#: 
CD006691
PEARLS No: 
166
Date: 
May, 2009
Authored by: 
Brian R McAvoy