Abnormal skeletal muscle capillary recruitment during exercise in patients with type 2 diabetes mellitus and microvascular complications

J Am Coll Cardiol. 2009 Jun 9;53(23):2175-83. doi: 10.1016/j.jacc.2009.02.042.


Objectives: 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.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Brachial Artery / physiology
  • Brachial Artery / physiopathology
  • Capillaries / pathology
  • Capillaries / physiopathology
  • Case-Control Studies
  • Diabetes Mellitus, Type 2 / diagnostic imaging
  • Diabetes Mellitus, Type 2 / physiopathology*
  • Diabetic Angiopathies / diagnostic imaging
  • Diabetic Angiopathies / physiopathology*
  • Exercise / physiology*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Muscle, Skeletal / blood supply*
  • Muscle, Skeletal / diagnostic imaging
  • Muscle, Skeletal / pathology
  • Regional Blood Flow
  • Ultrasonography