Impaired distal thermoregulation in diabetes and diabetic polyneuropathy.
OBJECTIVE
To determine how thermoregulation of the feet is affected by diabetes and diabetic polyneuropathy in both wakefulness and sleep.


METHODS
Normal subjects, diabetic subjects without neuropathy, diabetic subjects with small-fiber diabetic polyneuropathy, and those with advanced diabetic polyneuropathy were categorized based on neurological examination, nerve conduction studies, and quantitative sensory testing. Subjects underwent foot temperature monitoring using an iButton device attached to the foot and a second iButton for recording of ambient temperature. Socks and footwear were standardized, and subjects maintained an activity diary. Data were collected over a 32-h period and analyzed.


RESULTS
A total of 39 normal subjects, 28 patients with diabetes but without diabetic polyneuropathy, 14 patients with isolated small-fiber diabetic polyneuropathy, and 27 patients with more advanced diabetic polyneuropathy participated. No consistent differences in foot temperature regulation between the four groups were identified during wakefulness. During sleep, however, multiple metrics revealed significant abnormalities in the diabetic patients. These included reduced mean foot temperature (P < 0.001), reduced maximal temperature (P < 0.001), increased rate of cooling (P < 0.001), as well as increased frequency of variation (P = 0.005), supporting that patients with diabetic polyneuropathy and even those with only diabetes but no diabetic polyneuropathy have impaired nocturnal thermoregulation.


CONCLUSIONS
Nocturnal foot thermoregulation is impaired in patients with diabetes and diabetic polyneuropathy. Because neurons are highly temperature sensitive and because foot warming is part of the normal biology of sleep onset and maintenance, these findings suggest new potentially treatable mechanisms of diabetes-associated nocturnal pain and sleep disturbance.
Rutkove
Seward B
SB
Department of Neurology, Division of Neuromuscular Diseases, Harvard Medical School, Beth Israel Deaconess Medical Center, Boston, Massachusetts, USA. srutkove@bidmc.harvard.edu
Veves
Aristidis
A
Mitsa
Theophano
T
Nie
Rui
R
Fogerson
Patricia M
PM
Garmirian
Lindsay P
LP
Nardin
Rachel A
RA
D000328:Adult; D001833:Body Temperature Regulation; D002940:Circadian Rhythm; D003020:Clothing; D003920:Diabetes Mellitus / Q000503:physiopathology*; D003929:Diabetic Neuropathies / Q000145:classification / Q000503:physiopathology*; D004867:Equipment Design; D005260:Female; D005528:Foot / Q000502:physiology; D006706:Homeostasis / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory / Q000295:instrumentation / Q000379:methods; D009043:Motor Activity; D009068:Movement; D009412:Nerve Fibers / Q000473:pathology / Q000502:physiology; D009431:Neural Conduction / Q000502:physiology*; D012775:Shoes; D012890:Sleep; D014851:Wakefulness