Hypoglycaemia: symptoms can occur at normoglycaemic blood levels in diabetics

Clinical bottom line (level 5)

  1. Patients with diabetes experience symptoms of hypoglycaemia at higher blood glucose levels than patients without diabetes (on average 1.4 mmol/l higher)
Boyle et al: New England Journal of Medicine 1988; 318: 1487-1492
Expires October 2003

The study

Case-control study with objective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.
Setting: research laboratory, USA

18 patients (aged 28 to 37, mean 33, ?50% male)
Control Group: (n = 10, 10 analysed): patients without diabetes
Experimental Group: (n = 8, 8 analysed): diabetes (with HbA 1 levels > 10%, and no major chronic complications)
Patients had an insulin infusion overnight to maintain blood levels at 5.6 mmol/l. In the mornings this was gradually increased, so that blood glucose levels fell by 0.5 mmol/l every hour
100% followed for ?

The evidence

Outcome Control Group
(SD)		 Experimental Group
(SD)		 Mean Difference
(95% CI)
blood glucose levels at which hypoglycaemic symptoms developed (mmol/l) 2.9
(0.3) 		4.3
(0.9) 		1.4
(0.76 to 2.0)

Comments

  1. The highly physiologic nature of this investigation brings its clinical relevance into question.

Citation

  1. Boyle PJ, Schwartz NS, Shah SD, et al: plasma glucose concentrations at the onset of hypoglycemic symptoms in patients with poorly controlled diabetes and in nondiabetics. New England Journal of Medicine 1988; 318: 1487-1492
Contributor: Chris Ball and Clare Wotton, October 1999
Reviewer: Tadao Okada

Clinical Question.
Patient diabetes
Intervention or Exposure blood glucose level
Outcome symptoms of hypoglycaemia