Screening for sulphonylureas in the investigation of hypoglycaemia

Murder by insulin: suspected, purported and proven-a review

Murder by insulin-whether attempted, suspected or proven-is rare. Only 66 cases worldwide could be found for this review. A conviction was secured in 31 cases and additional weapon was employed in 11. Differentiation of attempted homicide from Munchausen syndrome by proxy in the young and from 'mercy killing' in the elderly was not attempted. Most perpetrators were close relatives and most victims were alive when discovered and responded to treatment. Hypoglycaemia is the first clue to homicidal insulin use in living subjects and requires the demonstration of a plasma insulin concentration of generally more than 1000 pmol/L and undetectable plasma C-peptide concentration to establish the diagnosis. Serum glucose measurements are valueless in victims found dead. The presence near the body of insulin vials, syringes or needles, loose talk by the suspected perpetrator or their ready access to insulin may be the only clue. The demonstration of insulin in tissue around an injection site by immunohistopathology or by measuring it in an extract clinches the diagnosis. Immunoassays suitable for clinical use to detect and measure insulin and C-peptide are subject to random errors and cannot be relied upon unless special precautions including separation by gel filtration or HPLC are undertaken prior to analysis. They do not detect or measure accurately a new generation of synthetic insulin analogues. Mass spectrometry will be required to do this and to validate clinical immunoassays, upon which convictions have always had to rely in the past.

[Hypoglycemia associated with oral sulfonylurea hypoglycaemic agents in an 11-year-old girl]

In children more than 8 years old, hyperinsulinism is the most common cause of hypoglycemia.

CASE REPORT

We report the case of an 11-year-old girl who presented recurrent hypoglycemia with endogenous hyperinsulinism (high insulin and C-peptide concentrations). The morphological investigations didn't find insulinoma. Finally the questioning identifies the voluntary intoxication with hypoglycemic agent. At a later date, the sulfonylurea dosage during an hypoglycaemic episode was positive.

CONCLUSION

The sulfonylurea drugs can mimic an endogenous hyperinsulinism and mislead the diagnostic to an insulinoma suspicion and lead to a surgical exploration. A sulfonylurea dosage should be done before planning out surgery.

Adult spontaneous hypoglycaemia

Spontaneous hypoglycaemia is not a diagnosis, but a manifestation of a disease process. It is important to recognize spontaneous hypoglycaemia, as treatment may be preventative or curative. It is equally important to avoid mislabelling healthy individuals as having hypoglycaemia as this may have a negative impact on the quality of life and use of scarce health-care resources.