The effects of dietary protein on physical performance and body composition in middle age and older people having type II diabetes mellitus: a randomized pilot study.

Purpose: Protein supplementation has been proposed as an effective dietary strategy for maintaining or increasing skeletal muscle mass and improving physical performance in middle-aged and older adults. Diabetes mellitus exacerbates muscle mass loss, leading to many older adults with type 2 diabetes mellitus (T2DM) experiencing sarcopenia, and vice versa. Our objective was to assess the impact of increased dietary protein intake on muscle mass, strength, physical performance, and the progression of T2DM in middle-aged and older adults diagnosed with this condition.

Methods: A 12-week randomized, controlled, parallel pilot study was conducted with 26 patients diagnosed with T2DM and had either low muscle mass, or low muscle strength or poor physical performance (age > 55 years old), aiming to investigate the effects of a protein-rich diet in sarcopenic and metabolic markers. The control group received 0.8-1.0 g/kg/day, while the intervention group received 1.2-1.5 g/kg/day of protein respectively. Body composition, muscle mass/strength and biochemical parameters were measured before and after the intervention period.

Results: Different kinetics of skeletal muscle index (SMI), appendicular lean mass (ALM), hand grip strength (HGS), gait speed (GS) and standing balance (SB) (p < 0.05) were observed between two groups. Specifically, the intervention group showed a significant improvement in HGS (p < 0.001) and physical performance (timed-up-and-go, p < 0.001; GS, p = 0.011; SB, p = 0.022), while the control group had its ALM (p = 0.014), SMI (p = 0.011) and HGS (p = 0.011) significantly reduced. The kinetics of metabolic markers indices was similar for both groups.

Conclusion: Current recommendation for protein intake (0.8-1 g/kg/day) is certainly not enough to ameliorate the muscle mass loss in middle age and older adults' individuals with T2DM. In contrast, protein intake of 1.2-1.5 g/kg/day seems to be a more appropriate recommendation to combat upcoming sarcopenia, nonetheless the progression of T2DM was not interrupted.