Absence of sexual dimorphism in the symptomatic responses to hypoglycemia in adults with and without type 1 diabetes

Modeling the consistency of hypoglycemic symptoms: high variability in diabetes

BACKGROUND

The aim of the present study was to examine symptoms of hypoglycemia, to develop a method to quantify individual differences in the consistency of symptom reporting, and to investigate which factors affect these differences.

METHODS

Participants recorded their symptoms with every episode of hypoglycemia over a 9-12-month period. A novel logistic-type latent variable model was developed to quantify the consistency of each individual's symptom complex and was used to analyze data from 59 subjects (median age, 57.5 years [range, 22-74 years], 65% male, 77% type 1 diabetes) who had experienced 19 or more hypoglycemic episodes. The association between the calculated consistency parameter and age, sex, type and duration of diabetes, and C-peptide and serum angiotensin converting enzyme concentration was examined using a generalized linear model. Analyses were performed under a Bayesian framework, using Markov chain Monte-Carlo methodology.

RESULTS

Individuals exhibited substantial differences in between-episode consistency of their symptom reports, with only a small number of individuals exhibiting high levels of consistency. Men were more consistent than women. No other factors affected consistency in patients with normal hypoglycemia awareness.

CONCLUSIONS

By using a novel stochastic model as a quantitative tool to compare the consistency of hypoglycemic symptom reporting, much greater intra-individual variability in symptom reporting was identified than has been recognized previously. This is relevant when instructing patients on identification of hypoglycemic symptoms and in interpreting symptomatic responses during experimentally induced hypoglycemia.

Effects of acute insulin-induced hypoglycaemia on psychomotor function: people with type 1 diabetes are less affected than non-diabetic adults

AIMS/HYPOTHESIS

We examined the effects of acute insulin-induced hypoglycaemia on psychomotor function in non-diabetic volunteers and in adults with type 1 diabetes.

METHODS

Non-diabetic adults (n = 20) and adults with type 1 diabetes mellitus (n = 16) each underwent a euglycaemic-hyperinsulinaemic glucose clamp on two separate occasions. Arterialised blood glucose was maintained for 1 h at either 4.5 mmol/l (euglycaemia) or 2.5 mmol/l (hypoglycaemia). During this time participants underwent neuropsychological tests to assess psychomotor function.

RESULTS

During hypoglycaemia the non-diabetic participants showed a significant deterioration in the following: (1) four-choice reaction time (p = 0.008); (2) grooved pegboard (a test of manual dexterity; p = 0.004); (3) hand steadiness (p = 0.003); (4) pursuit rotor (a test of fine motor function, attention and coordination; p = 0.018); and (5) test of total body coordination (p = 0.004). No significant differences were observed between euglycaemia and hypoglycaemia in hand-grip (p = 0.897) and line tracing time (p = 0.480) tests. In type 1 diabetes mellitus patients, only four-choice reaction time (p = 0.023) and pursuit rotor (p = 0.045) were impaired significantly during hypoglycaemia.

CONCLUSIONS/INTERPRETATION

Although acute hypoglycaemia caused significant impairment of several psychomotor functions in non-diabetic adults, a lower magnitude of impairment was observed in those with type 1 diabetes. The mechanism underlying this discrepant effect of hypoglycaemia on psychomotor function remains unknown, but may be related to the difference in sympathoadrenal activation observed between the groups. People with type 1 diabetes may also have had a behavioural advantage of over non-diabetic participants derived from their previous exposure to hypoglycaemia or potentially the disparate results arose from hypoglycaemia-induced cerebral adaptation.