Diabetes has been shown to cause a loss in muscle strength and mass due to decreasing insulin signalling and increasing insulin resistance. For people with type 2 diabetes, maintaining muscle mass is crucial because muscle is a main organ for glucose metabolism.
In older people with type 2 diabetes, loss of muscle mass is associated to increasing risk of sarcopenia, cardiovascular disease and mortality.
Studies have shown vitamin D is effective for the prevention of muscle loss, lower vitamin B12 is associated with sarcopenia, and vitamin C and E associated with fraility, however their effects on older people with diabetes is unknown.
For this study, researchers in Japan wanted to establish the relationship between vitamins A, B1, B2, B6, B12, C, D and E and the loss of muscle mass in older people with type 2 diabetes.
The results were published in the journal Nutrients.
Forming part of the KAMOGAWA-DM cohort study on people with diabetes mellitus, the current study involved 197 individuals with type 2 diabetes who were recruited between 2016 to 2018.
At baseline and follow-up visits, a multifrequency impedance body composition analyser was used to evaluate body composition and food intake recorded.
Muscle mass loss was calculated as a percentage reduction from baseline to follow-up. A rate of ≥1.2% was considered as loss of muscle mass.
Among the 197 people, 47.2% of them experienced a loss of muscle mass at an average of 13-month follow-up.
Among these people, their intake of vitamin B1, B12 and D was significantly lower than participants without muscle mass loss.
Previous studies have revealed that low serum vitamin D levels increased the risks of loss of muscle strength and mass and frailty. In this study, serum vitamin D levels were not measured, and may be considered for future studies.
Previous studies also revealed that supplementation of vitamin D in people with prediabetes or insulin resistance and inadequate vitamin D levels improves insulin sensitivity in skeletal muscle, which is key in the current group of subjects with type 2 diabetes.
Vitamin B12 is known to affect sarcopenia, because it helps to lower serum levels of homocysteine. High levels of homocysteine is related to the loss of muscle strength and gait speed.
For vitamin B1, insufficient intake is known to cause inadequate glucose metabolism in the mitochondria which leads to muscle loss.
“To prevent the loss of muscle mass in older people with type 2 diabetes having a higher risk of the loss of muscle mass, we should consider not only macronutrient intake, such as energy and protein intakes, but also micronutrient intake, such as vitamin D intake in older people with type 2 diabetes,” they wrote.
In this study, vitamin A, C, and E intakes were not associated with the loss of muscle mass.
Vitamin A is known for its effect on activating immune function, while vitamin C and E are antioxidants. Researchers said further study is needed to understand this finding.
The study had several limitations including how supplements used by participants were not identified, and that data on eating habits were obtained at baseline and may have changed during the follow-up period.
In addition, serum vitamin D, vitamin B12, and homocysteine levels were not measured and also did not consider vitamin D produced by the skin under ultraviolet ray, hence the current study could not account for total vitamin D status in the body.
“Vitamin Intake and Loss of Muscle Mass in Older People with Type 2 Diabetes: A Prospective Study of the KAMOGAWA-DM Cohort”
Authors: Fuyuko Takahashi, et al.