The effect of hyperglycaemia on cerebral potentials evoked by rapid rectal distension in healthy humans

Effect of acute hyperglycaemia on sensory processing in diabetic autonomic neuropathy

BACKGROUND

Acute hyperglycaemia is known to increase gastrointestinal (GI) sensitivity in healthy subjects and may contribute to the increased prevalence of GI symptoms in diabetes patients. The aim of this study was to evaluate the effect of acute hyperglycaemia on perception and brain responses to painful visceral and somatic stimuli in diabetic patients.

MATERIALS AND METHODS

The sensitivity and evoked brain potentials (EPs) to electrical oesophageal and median nerve stimulations were assessed in 14 type-1 diabetes patients with autonomic neuropathy and GI symptoms using a hyperinsulinaemic clamp at 6 and 15 mM.

RESULTS

No differences between the normo- and hyperglycaemic conditions were found in sensitivity to both oesophageal (P=0·72) and median nerve (P=0·66) stimulations. The latencies and amplitudes of EPs did not differ between the normo- and hyperglycaemic conditions following oesophageal (P=0·53 and 0·57) and median nerve (P=0·78 and 0·52) stimulations.

CONCLUSIONS

Acute hyperglycaemia itself does not contribute to the sensations in patients with longstanding diabetes and autonomic neuropathy. Any potential sensory effects of acute hyperglycaemia can likely be blurred by the neuropathic-like changes in the sensory nervous system.

Control of hyperglycaemia in paediatric intensive care (CHiP): study protocol

BACKGROUND

There is increasing evidence that tight blood glucose (BG) control improves outcomes in critically ill adults. Children show similar hyperglycaemic responses to surgery or critical illness. However it is not known whether tight control will benefit children given maturational differences and different disease spectrum.

METHODS/DESIGN

The study is an randomised open trial with two parallel groups to assess whether, for children undergoing intensive care in the UK aged <or= 16 years who are ventilated, have an arterial line in-situ and are receiving vasoactive support following injury, major surgery or in association with critical illness in whom it is anticipated such treatment will be required to continue for at least 12 hours, tight control will increase the numbers of days alive and free of mechanical ventilation at 30 days, and lead to improvement in a range of complications associated with intensive care treatment and be cost effective. Children in the tight control group will receive insulin by intravenous infusion titrated to maintain BG between 4 and 7.0 mmol/l. Children in the control group will be treated according to a standard current approach to BG management. Children will be followed up to determine vital status and healthcare resources usage between discharge and 12 months post-randomisation. Information regarding overall health status, global neurological outcome, attention and behavioural status will be sought from a subgroup with traumatic brain injury (TBI). A difference of 2 days in the number of ventilator-free days within the first 30 days post-randomisation is considered clinically important. Conservatively assuming a standard deviation of a week across both trial arms, a type I error of 1% (2-sided test), and allowing for non-compliance, a total sample size of 1000 patients would have 90% power to detect this difference. To detect effect differences between cardiac and non-cardiac patients, a target sample size of 1500 is required. An economic evaluation will assess whether the costs of achieving tight BG control are justified by subsequent reductions in hospitalisation costs.

DISCUSSION

The relevance of tight glycaemic control in this population needs to be assessed formally before being accepted into standard practice.

Influence of acute hyperglycaemia on the amplitude of nociceptive spinal evoked potentials in healthy rats

To evaluate the effect of blood glucose level on the amplitude of nociceptive spinal evoked potentials in healthy rats, an acute hyperglycaemia state was induced in an experimental group of 12 rats, through the infusion of glucosade solution. A Ringer-lactate solution was administered equivolumetrically to the control group (5 rats) under the same experimental conditions. Nociceptive spinal evoked potentials were recorded every 2 min, before and during the induction of hyperglycaemia, from the left lumbar cord dorsum activated orthodromically by ipsilateral electrical stimulation of the hind paw (20 Volts, 0.5 ms, 0.2 Hertz). Acute hyperglycaemia induced an increase of amplitude in both N (+8.92%, p = .000006) and P (+10.46%, p = .000037) waves when comparing control and experimental groups or basal versus infusion values, in response to nociceptive stimuli. The present results show that acute hyperglycaemia could contribute to central nociceptive sensitization; it would be attributed to an increased synchronization of spinal dorsal horn neuronal discharges.

Effects of acute hyperglycaemia on anorectal motor and sensory function in diabetes mellitus

AIMS

To determine the effects of acute hyperglycaemia on anorectal motor and sensory function in patients with diabetes mellitus.

METHODS

In eight patients with Type 1, and 10 patients with Type 2 diabetes anorectal motility and sensation were evaluated on separate days while the blood glucose concentration was stabilized at either 5 mmol/l or 12 mmol/l using a glucose clamp technique. Eight healthy subjects were studied under euglycaemic conditions. Anorectal motor and sensory function was evaluated using a sleeve/sidehole catheter, incorporating a barostat bag.

RESULTS

In diabetic subjects hyperglycaemia was associated with reductions in maximal (P<0.05) and plateau (P<0.05) anal squeeze pressures and the rectal pressure/volume relationship (compliance) during barostat distension (P<0.01). Hyperglycaemia had no effect on the perception of rectal distension. Apart from a reduction in rectal compliance (P<0.01) and a trend (P=0.06) for an increased number of spontaneous anal sphincter relaxations, there were no differences between the patients studied during euglycaemia when compared with healthy subjects.

CONCLUSIONS

In patients with diabetes, acute hyperglycaemia inhibits external anal sphincter function and decreases rectal compliance, potentially increasing the risk of faecal incontinence.

The effect of acute hyperglycaemia on appetite and food intake in Type 1 diabetes mellitus

AIMS

To determine the effects of acute hyperglycaemia on appetite and food intake in Type 1 diabetes mellitus.

METHODS

Two separate studies, each involving eight adults with uncomplicated Type 1 diabetes, were performed: one in the fasted state (A) and the other after a nutrient preload (B). In both studies, perceptions of appetite (hunger and fullness) and food intake at a buffet meal were evaluated during euglycaemia (blood glucose, approximately 6 mmol/l) and hyperglycaemia (blood glucose, approximately 14 mmol/l). Both experiments were randomized and single-blind. In study A, appetite was assessed in the fasted state for 90 min before the buffet meal. In study B, a nutrient 'preload' of Ensure and milk containing 13C-octanoic acid was consumed 90 min before the meal. Gastric emptying of the preload was quantified with a radioisotopic breath test technique.

RESULTS

There was no significant difference in plasma insulin concentrations between euglycaemia and hyperglycaemia in either study. In study A, there were no differences in hunger, fullness or energy intake between the two treatment days. In study B, subjects were slightly less hungry between the preload and buffet meal during hyperglycaemia than euglycaemia (P = 0.04), and tended to have slower gastric emptying during hyperglycaemia (emptying coefficient, 3.89 +/- 0.16 vs. 3.57 +/- 0.21; P = 0.052), but there was no difference in food intake between hyperglycaemia and euglycaemia.

CONCLUSIONS

Acute hyperglycaemia suppresses hunger after a nutrient preload, but not in the fasted state, in patients with uncomplicated Type 1 diabetes. This effect is small and not associated with changes in food intake.

Manometric assessment of anorectal function

A diagnostic test is useful if it can provide information regarding the underlying pathophysiology, confirm a clinical suspicion, or guide clinical management. In a prospective study, anorectal manometry was shown not only to confirm a clinical impression, but also to provide new information that was not detected clinically. The information obtained from these studies influenced the management and outcome of patients with defecation disorders (Table 1). These findings have been confirmed further by another study that showed colorectal physiologic tests provided a definitive diagnosis in 75% of patients with constipation, 66% of patients with incontinence, and 42% of patients with intractable anorectal pain. A systematic and careful appraisal of anorectal function can provide invaluable information that can guide treatment of patients with anorectal disorders. A more uniform method of performing these tests and interpreting the results is needed to facilitate a wider use of this technology for the assessment of patients with anorectal disorders.