Insulin Sensitizers Limit Muscle Loss in Older Diabetes Patients

Lead author Dr. Christine G. Lee from Oregon Health and Science University in Portland stated that, it's unclear "how insulin sensitizers (particularly metformin) may work to preserve muscle mass."  "Understanding their mechanism of action on muscle may also lead to the development of more preventive therapies for sarcopenia," she noted.

Dr. Lee and colleagues analyzed longitudinal data on 3752 older men who were participating in the Osteoporotic Fractures in Men study (MrOS). All were at least 65 years old at baseline. Most (1853) had normoglycemia, 1403 had IFG, 234 had untreated diabetes, 151 had diabetes treated with insulin sensitizers, and 111 had diabetes treated without insulin sensitizers.

During a mean follow-up of 3.5 years, mean total lean mass decreased in all groups, by 1.4% in diabetics treated with insulin sensitizers, 1.7% in normoglycemic men, 1.9% in men with IFG, 2.9% in untreated diabetics, and 3.0% in diabetics treated without insulin sensitizers.

Loss of appendicular lean mass followed the same pattern.

Diabetics treated with thiazolidinediones and normoglycemic men had similar patterns of total and appendicular lean mass loss. Diabetics who received metformin lost slightly less total and appendicular lean mass compared to normoglycemic men, but the difference was not statistically significant.

But when diabetics received both metformin and thiazolidinediones, they actually ended up with more total and appendicular lean mass than the normoglycemic men.

Moreover, men treated with metformin, with or without a thiazolidinedione, lost significantly less total and appendicular lean mass than untreated diabetics or diabetics treated without insulin sensitizers.

"These are observational findings, and a clinical trial is needed to validate these findings before considering any changes to the management of older adults with IFG and diabetes," Dr. Lee said. "At least from our study and others, clinicians should be aware that older adults with diabetes may lose more muscle mass and strength than older adults without diabetes."

"To understand the clinical relevance of muscle loss, we are currently examining how the percentage change in lean mass is associated with changes in physical performance and muscle strength," Dr. Lee said. "We at least know that losing 5% lean mass or greater over 4.6 years is associated with an increased risk of mortality."

"Perhaps future diabetes studies in older adults should examine the effects of various treatments on functional outcomes and not just focus on macro- or microvascular complications or mortality," Dr. Lee added.