Does acute hyperglycaemia influence heat pain thresholds?

Abstract

SUMMARY The influence of acute hyperglycaemia on pain sensation was assessed in eight young adult non-diabetic subjects. Acute hyperglycaemia was induced with IV glucose in a double blind fashion, with IV saline as a control. Pain thresholds were assessed by a painful heat stimulus delivered by a Marstock thermode on the thenar eminence. Heat pain thresholds did not significantly alter during either acute hyperglycaemia or the control saline infusion. Previous work demonstrating a lowering of electrical pain thresholds by hyperglycaemia has therefore not been confirmed using a natural painful stimulus.Experimental work in animals has shown that hyperglycaemia can reduce the antinociceptive potency of morphine.' Morley et al2 have shown that acute hyperglycaemia lowered thresholds to painful electrical stimulation in normal human subjects. These findings are compatible with the hypothesis that hyperglycaemia, or rapid fluxes in blood glucose levels, increase pain sensitivity. They also showed that diabetic subjects had a lower pain tolerance compared with non-diabetic controls. Morley and colleagues conclude from their studies that glucose may modulate opioid receptors in man. A recent editorial called for further work on the association between hyperglycaemia, pain perception, and possible glucose modulation of opioid receptors.3 Electrical stimuli of sufficient intensity to activate nociceptive fibres will perforce generate impulses in every other kind of nerve fibre. Therefore, we favour the use of a noxious heat stimulus, which selectively activates small Ab and C fibres.45 We assessed the influence of hyperglycaemia on pain thresholds using a noxious heat stimulus, delivered by a Marstock thermode.6 Subjects Eight healthy, non-diabetic subjects (4 male), mean age 25 years (range 18-38), were studied. All had normal fasting blood glucose (< 6 mmol/l) and glycosylated haemoglobin values of less than 7% (laboratory reference: 5-8%), and were taking no medications. MethodsThe subjects were studied after an overnight fast and all experiments were conducted in a quiet room with an ambient temperature of 19°C. Two intravenous cannulae were inserted, one in each antecubital fossa. Each subject was tested twice in a randomised, double blind, crossover study to receive either an intravenous bolus of 50 gram glucose in 100 ml or an equivalent volume of normal saline. The alternative injection was given a week later. All injections were made over a period of 2 minutes. Venous blood for glucose estimation was taken at 15 minutes before injection (fasting), and 0,5,10, 20, 30, 40, 50, 60 minutes afterwards. Heat pain and cold thresholds (HPT and CT) were obtained with a Marstock thermode attached to the thenar eminence of the non-dominant hand and held in place by a small weight.6 A constant current of 2 A was delivered to the stimulating plate and the test subject indicated the perceived thermal threshold by pressing a switch which reversed the direction of the current and therefore of the temperature change. The thermo...

Painful diabetic neuropathy

“…However, Chan et al . found no alteration in thermal pain thresholds during acute hyperglycaemia in either normal or diabetic subjects[52, 53]. In diabetic patients, chronic painful neuropathic symptoms can be relieved by an improvement in metabolic control[54] although, paradoxically, acute neuropathic pain can be precipitated by marked reductions of blood glucose[34, 55].…”

Selective Nerve Root Stimulation (SNRS) in the Treatment of End-Stage, Diabetic, Peripheral Neuropathy: A Case Report

“…This continuous symptomology may lead to fatigue, insomnia, situational dysfunction (anxiety/dysthymia), progressive atrophy, deconditioning, and severe functional disability ( 8‐10). The cause of chronic diabetic neuropathic pain is not well known, although multifactorial metabolic, autoimmune, and microvascular system elements may be involved ( 11‐13).…”

Symptomatische Behandlung schmerzhafter diabetischer Neuropathien

“…In der gleichen Untersuchung war die Schmerztoleranz, der maximal tolerierte Schmerz, bei Typ-2-Diabetikern bei höheren mittleren Blutglukosekonzentrationen geringer als bei gesunden Kontrollen. Andere Beobachtungen sprechen gegen eine Bedeutung der aktuellen Blutzuckerkonzentration: Bei Stoffwechselgesunden wurde die Hitzeschmerzschwelle nicht durch die aktuelle Blutglukosekonzentration beeinflusst [12]. Bei Typ-1-Diabetikern zeigte die Schmerzintensität während eines "cold pressor test" keinen Zusammenhang mit der aktuellen Blutzuckerkonzentration [32].…”