Muscle weakness and atrophy of the lower limbs may develop in patients with
diabetes, increasing their risk of falls. The underlying basis of these
abnormalities has not been fully explained. The aim of this study was to
objectively quantify muscle strength and size in patients with type 2
diabetes mellitus (T2DM) in relation to the severity of neuropathy,
intramuscular noncontractile tissue (IMNCT), and vitamin D deficiency.
DESIGN AND METHODS: Twenty patients with T2DM and 20 healthy control subjects
were matched by age, sex, and BMI. Strength and size of knee extensor,
flexor, and ankle plantar and dorsiflexor muscles were assessed in relation
to the severity of diabetic sensorimotor polyneuropathy (DSPN), amount of
IMNCT, and serum 25-hydroxy vitamin D (25OHD) levels.
Compared with control subjects, patients with T2DM had significantly reduced
knee extensor strength (P = 0.003) and reduced muscle volume of both knee
extensors (P = 0.045) and flexors (P = 0.019). Ankle plantar flexor strength
was also significantly reduced (P = 0.001) but without a reduction in ankle
plantar flexor (P = 0.23) and dorsiflexor (P = 0.45) muscle volumes. IMNCT
was significantly increased in the ankle plantar (P = 0.006) and dorsiflexors
(P = 0.005). Patients with DSPN had significantly less knee extensor strength
than those without (P = 0.02) but showed no difference in knee extensor
volume (P = 0.38) and ankle plantar flexor strength (P = 0.21) or volume (P =
0.96). In patients with <25 nmol/L versus >25 nmol/L 25OHD, no
significant differences were found for knee extensor strength and volume (P =
0.32 vs. 0.18) and ankle plantar flexors (P = 0.58 vs. 0.12).
Patients with T2DM have a significant reduction in proximal and distal leg
muscle strength and a proximal but not distal reduction in muscle volume
possibly due to greater intramuscular fat accumulation in distal muscles.
Proximal but not distal muscle strength is related to the severity of
peripheral neuropathy but not IMNCT or 25OHD level.