1293

Factitious Hypoglycæmia

THE LANCET

OVER the past decade, first in America, later inBritain, people have increasingly attributed theirills-and especially those ills for which doctorshave failed to discover an organic explanation-toa low blood-glucose. This belief seems erroneous.In one study, of 30 patients referred with a diag-nosis of hypoglycaemia, half proved to be psychia-trically ill (usually with depression), many had hys-terical personality traits, and the prevalence ofabnormalities bore no relation to glucose-tolerance-test findings. YAGER and YouNG2 went so far as todescribe "non-hypoglycemia" as an epidemic con-dition providing a socially acceptable diagnosis forthe mentally ill. Against this background, organichypoglycxmia has to be diagnosed with great care.3Recognition of reactive hypoglycaemia is usuallyfairly simple and the condition can often be associ-ated with rapid gastric emptying or the "prodro-mal" phase of maturity-onset diabetes.4 Alcoholmust also be given thought as a cause of hypo-glycxmia both after carbohydrates and in the fast-ing state.6 The fasting response to alcohol was thebasis for the first suppression test for insulinoma,7a cause of fasting hypoglycsemia that every clin-ician is anxious not to overlook.

Another rare diagnosis, also easily overlooked, isfactitious hypoglyceemia-that is, hypoglycxmiadeliberately self-induced with insulin or an oralhypoglycxmia agent. This condition is virtuallylimited to two groups of people-established dia-betics on insulin, and medical personnel, especially

1. Ford, C. V., Bray, G. A., Swerdloff, R. S. Am. J. Psychiat. 1976, 133, 290.2. Yager, J., Young, R. T. New Engl. J. Med., 1974, 291, 907.3. Cahill, G. F., Soeldner, J. S. ibid. p. 905.4. Seltzer, H. S., Fajans, S. S., Conn, J. W. Diabetes, 1956, 5, 437.5. O’Keefe, S. J., Marks, V. Lancet, 1977, i, 1286.6. Field, J. B., Williams, H. E., Mortimore, G. E. J. clin. Invest. 1963, 42, 497.7 Turner, R. C, Oakley, N. W., Nabarro, J. D. N. Br Med J. 1971, ii, 132.

nurses.8 In the former group, teenage girls pre-dominate, young female diabetics being particu-larly prone to a wide range of behaviour distur-bances. Factitious hypoglycsemia springs less

readily to mind when a medically connected patientpresents with bizarre symptoms; yet the connectionwas well known to Rus SELL WILDER early in the daysof insulin use.8 There are now over twenty reportsof factitious hypoglycaemia, most of which are men-tioned by ScaRt,ETT et a1.l who used C-peptideassay and insulin-binding-antibody estimations inpatients suspected of clandestine insulin adminis-tration. Seven patients are described-all nurses,medical technicians, children of nurses, or patientswith a history of diabetes-and exogenous insulinadministration was diagnosed from the triad of lowplasma glucose, high immunoreactive insulin, andsuppressed C-peptide immunoreactivity. In two pa-tients, insulin-binding antibodies were detected,while estimation of plasma free insulin enabled adiagnosis to be made in subjects with a history ofinsulin-treated diabetes. The diagnostic techniquesdescribed are ingenious, but care is needed in theinterpretation of plasma-insulin and C-peptide datain hypoglycaemic subjects since patients with undif-ferentiated insulinomas may secrete proinsulinrather than insulin and C-peptide-a findingwhich has led to the conclusion that estimation of

proinsulin, rather than C-peptide or insulin, duringinduced hypoglycxmia, provides the best test forinsulinomas,10 though proinsulin assay is complexand not generally available.A sinister facet of factitious hypoglycaemia is the

frequency of criminal injections; two of the casesdescribed by ScARLETT et a1.9 administered insulinto their children, one with fatal results, while atleast one murder with insulin has been committedin Britain; this was notable also for being the firstinstance of forensic insulin assay. Another death,a tragic case of projected mercy-killing and suicide,led to a recent charge of murder.The physician confronted with "hypoglycxmia"

now faces a tricky task. Firstly, he has to be ableto decide whether the diagnosis is a true one-andthe normal plasma-glucose may become very low inhealthy subjects, notably premenopausal women. 11Secondly, he has to establish the cause of hypo-glycxmia. Yet while the latter seems to be dependingmore and more on complicated assays of proinsulinand its fragments, a clear message comes throughall writings on this subject that a careful clinicalhistory, a suspicious mind, and a few simplemeasurements and observations can lead to the cor-rect diagnosis in the great majority of cases.

8. Oakley, W. G. Trans. Med. Soc. Lond. 1961, 78, 1.9. Scarlett, J. A., et al. New Engl. J. Med. 1977, 297, 1029.

10. Turner, R. C., Heding, L. G. Diabetologia, 1977, 13, 571.11. Merimee, T. J., Tyson, J. E. New Engl J. Med 1974, 291, 1275.