Distal lower limb strength is reduced in subjects with impaired glucose tolerance and is related to elevated intramuscular fat level and vitamin D deficiency

• Published in: Diabetic medicine Vol. 34; no. 3; pp. 356 - 363
• Main Authors: Almurdhi, M. M., Reeves, N. D., Bowling, F. L., Boulton, A. J. M., Jeziorska, M., Malik, R. A.
• Format: Journal Article
• Language: English
• Published: England Wiley Subscription Services, Inc 01.03.2017
• Subjects: 25-Hydroxyvitamin D 2 - blood; Adiposity; Aged; Ankle; Calcifediol - blood; Diabetes; Early Diagnosis; Female; Glucose; Glucose Intolerance - complications; Glucose Intolerance - metabolism; Glucose Intolerance - pathology; Glucose Intolerance - physiopathology; Humans; Knee; Leg; Lipid Metabolism; Magnetic Resonance Imaging; Male; Middle Aged; Muscle Strength; Muscle Weakness - complications; Muscle Weakness - diagnostic imaging; Muscle Weakness - physiopathology; Muscle, Skeletal - diagnostic imaging; Muscle, Skeletal - metabolism; Muscle, Skeletal - pathology; Muscle, Skeletal - physiopathology; Polyneuropathies - complications; Polyneuropathies - diagnosis; Polyneuropathies - physiopathology; Severity of Illness Index; Small Fiber Neuropathy - complications; Small Fiber Neuropathy - diagnosis; Small Fiber Neuropathy - physiopathology; Vitamin D; Vitamin D Deficiency - complications; Vitamin D Deficiency - diagnosis; Vitamin D Deficiency - physiopathology; Vitamin deficiency
• ISSN: 0742-3071; 1464-5491
• DOI: 10.1111/dme.13163

Aim To quantify muscle strength and size in subjects with impaired glucose tolerance (IGT) in relation to intramuscular non‐contractile tissue, the severity of neuropathy and vitamin D level. Methods A total of 20 subjects with impaired glucose tolerance and 20 control subjects underwent assessment of strength and size of knee extensor, flexor and ankle plantar and dorsi‐flexor muscles, as well as quantification of intramuscular non‐contractile tissue and detailed assessment of neuropathy and serum 25‐hydroxy vitamin D levels. Results In subjects with impaired glucose tolerance, proximal knee extensor strength (P = 0.17) and volume (P = 0.77), and knee flexor volume (P = 0.97) did not differ from those in control subjects. Ankle plantar flexor strength was significantly lower (P = 0.04) in the subjects with impaired glucose tolerance, with no difference in ankle plantar flexor (P = 0.62) or dorsiflexor volume (P = 0.06) between groups. Intramuscular non‐contractile tissue level was significantly higher in the ankle plantar flexors and dorsiflexors (P = 0.03) of subjects with impaired glucose tolerance compared with control subjects, and it correlated with the severity of neuropathy. Ankle plantar flexor muscle strength correlated significantly with corneal nerve fibre density (r = 0.53; P = 0.01), a sensitive measure of small fibre neuropathy, and was significantly lower in subjects with vitamin D deficiency (P = 0.02). Conclusions People with impaired glucose tolerance have a significant reduction in distal but not proximal leg muscle strength, which is not associated with muscle atrophy, but with increased distal intramuscular non‐contractile tissue, small fibre neuropathy and vitamin D deficiency. What's new? There are no studies on the structure and function of lower limb muscles in people with impaired glucose tolerance (IGT). We believe such a study may provide insights into the early mechanisms of motor dysfunction in people with Type 2 diabetes. People with IGT have a significant reduction in distal but not proximal leg muscle strength and no evidence of proximal or distal muscle atrophy. Distal weakness was associated with increased distal intramuscular non‐contractile tissue, small fibre neuropathy and vitamin D deficiency in subjects with IGT.