Prevalence of factitious hypoglycaemia associated with sulphonylurea drugs in France in the year 2000

Hypoglycaemia presents important diagnostic and therapeutic problems. Severe and repetitive hypoglycaemic episodes without treatment may be difficult to explain. Failure to identify factitious hypoglycaemia may lead to laparotomy or pancreatectomy [1, 2].

To estimate the prevalence of factitious hypoglycaemia due to sulphonylurea drugs in patients with unexplained severe hypoglycaemia, we conducted a prospective study during the year 2000. Hypoglycaemic patients were recruited throughout France. Plasma was assayed for oral hypoglycaemic agents on the clinician's request, using h.p.l.c. with u.v. detection. Fifty-six patients with unexplained hypoglycaemia were recruited. In seven of these patients (five women, two men), a sulphonylurea oral hypoglycaemic agent was detected (Table 1).

Table 1.

Plasma concentrations observed.

Hypoglycaemic agent	Maximal concentrations observed	Therapeutic range	Elimination half-life
Glibenclamide (n = 4)	696 µg l−1	25–50 µg l−1	5 h−10 h
Glimepiride (n = 2)	418 µg l−1	300 µg l−1	5 h−9 h
Gliclazide (n = 1)	2.1 mg l−1	1.5 mg l−1	8 h−12 h

Plasma concentrations were usually supra-therapeutic and concentrations up to 15 times the upper limit of the therapeutic range were observed.

In one 45-year-old patient, during hospitalization, we identified glibenclamide concentrations of 529 µg l⁻¹ at 11.00 h (therapeutic concentration 25–50 µg l⁻¹), of 696 µg l⁻¹ at 22.00 h, of 154 µg l⁻¹ at 06.15 h and of 367 µg l⁻¹ at 08.00 h over a 2 day period.

Insulinoma has been suspected in such patients due to continued surreptitious consumption of medication during hospitalization.

Cases of factitious hypoglycaemia from oral hypoglycaemic agents have been published [1–4], and may be a manifestation of Munchausen's syndrome [5]. Factitious hypoglycaemia due to sulphonylurea drugs should be considered in the differential diagnosis of insulinoma.