Abnormal skeletal muscle capillary recruitment during exercise in patients with type 2 diabetes mellitus and microvascular complications.
OBJECTIVE
We sought to determine whether skeletal muscle capillary recruitment is impaired in type 2 diabetes mellitus (DM) with and without microvascular complications (MC).


BACKGROUND
Insulin and exercise each stimulate recruitment of skeletal muscle capillaries. Insulin-mediated recruitment is impaired in insulin-resistant humans and animals, but exercise-mediated recruitment has not been studied.


METHODS
We studied 20 control subjects, 22 patients with DM, and 8 patients with DM + MC. With the patients under fasting conditions, contrast-enhanced ultrasound perfusion imaging of the forearm flexor muscles was performed to evaluate capillary blood flow and blood volume at rest and during low- or high-intensity contractile exercise (25% and 80% maximal handgrip). Rheologic parameters of erythrocyte deformability and plasma viscosity were measured.


RESULTS
Muscle capillary responses to exercise were similar between the control and DM groups, but were reduced (p < 0.05) in those with DM + MC. The DM + MC group had a approximately 50% reduction in capillary recruitment and a approximately 60% to 70% reduction in capillary blood flow during both low- and high-intensity exercise compared with the control group. These abnormalities were independent of disease duration. Patients with DM + MC were more insulin resistant than DM patients and had an elevated whole blood viscosity that correlated with plasma glucose (p = 0.001) and C-reactive protein (p = 0.003).


CONCLUSIONS
Capillary recruitment during low- and high-intensity exercise is normal in uncomplicated type 2 DM but is impaired in those with microvascular complications. Abnormalities in capillary recruitment may be related to abnormal hemorheology, although larger trials are needed to establish this relation.
Womack
Lisa
L
General Clinical Research Center, University of Virginia, Charlottesville, USA.
Peters
Dawn
D
Barrett
Eugene J
EJ
Kaul
Sanjiv
S
Price
Wendie
W
Lindner
Jonathan R
JR
D001916:Brachial Artery / Q000502:physiology / Q000503:physiopathology; D002196:Capillaries / Q000473:pathology / Q000503:physiopathology; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000000981:diagnostic imaging / Q000503:physiopathology*; D003925:Diabetic Angiopathies / Q000000981:diagnostic imaging / Q000503:physiopathology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000000981:diagnostic imaging / Q000473:pathology; D012039:Regional Blood Flow; D014463:Ultrasonography