Identification of factors associated with impaired hypoglycaemia awareness in patients with type 1 and type 2 diabetes mellitus.

OBJECTIVES: To assess clinical factors associated with impaired hypoglycaemia awareness (HA).
METHODS: Survey of 241 type 1 and type 2 diabetic patients hospitalised in a diabetes department for a diabetes education program. Demographic, diabetes and psychiatric characteristics and subjective hypoglycaemic symptoms were recorded by a self-report questionnaire.
RESULTS: Age and body mass index (BMI) was greater and glycated haemoglobin was lower in diabetic patients reporting impaired HA, however, these latter differences became not significant when age was included as a covariate. There were significantly more current smokers among those with impaired HA and controlling for age accentuated this difference. Current treatment by insulin was not associated with impaired HA. Backward stepwise logistic regression showed that type 2 diabetic patients were twice as likely to have impaired HA than type 1 diabetic patients (OR = 2.195, 95% CI: 1.017-4.734, P = 0.04). Moreover, higher age, current smoking and type 2 diabetes interacted significantly in increasing the likelihood of impaired HA. Among those with impaired HA more patients experienced drowsiness and nervousness and less patients reported tremor during the hypoglycaemic episodes. No other symptoms were associated with impaired HA.
CONCLUSION: Type 2 diabetic patients, whether on insulin or not, and especially if they are of advanced age and if they smoke, are at increased risk of impaired HA.