Correspondence

Hypoglycemic Disorders

N Engl J Med 1995; 333:1154-1155October 26, 1995

Article

To the Editor:

We do not fully agree with Dr. Service (April 27 issue)1 on the evaluation of patients with hypoglycemia. In our hospital-based endocrinology group, we see 40 to 50 patients a year who are referred with this diagnosis. Many of them have had a determination of a low plasma glucose level with or without symptoms, thus warranting evaluation according to Dr. Service's article. These patients fit into all three categories — healthy-appearing, ill-appearing, and hospitalized. The vast majority, however, appear healthy and are not in the hospital. Dr. Service mentions that a history of neuroglycopenic symptoms warrants further testing and suggests that a reflectance meter is inadequate for screening purposes. He suggests first taking a detailed history. However, neuroglycopenic symptoms, such as weakness, confusion, difficulty in thinking, fatigue, and drowsiness, are very common among such patients. That would mean that these 40 patients would need 72-hour fasts, which according to his protocol would be costly.

The vast majority of this group may be taken care of by simply teaching them the technique of monitoring blood glucose levels at home with a reflectance meter. For glucose values in the normal range, these meters are quite accurate. Measurements made with them during the occurrence of spontaneous symptoms may provide some false positive results, but we use them daily with our patients who have intensively controlled insulin-dependent diabetes mellitus (IDDM). Dr. Service indicates that the bedside reflectance meter may have to serve as a guide to glucose levels in hospitalized patients when we are deciding whether to terminate the 72-hour fast. It appears, then, that if the meter shows normal values we should be willing to accept them.

V.K. Piziak, M.D.
A. Keith Cryar, M.D.
Scott and White Clinic, Temple, TX 76508

1 References

1. 1

   Service FJ. Hypoglycemic disorders. N Engl J Med 1995;332:1144-1152
   Full Text | Web of Science | Medline

To the Editor:

In his excellent review of hypoglycemic disorders, Dr. Service does not include falciparum malaria, perhaps the most prevalent cause of hypoglycemia in developing countries. Without treatment, falciparum malaria can cause severe hypoglycemia. The severity of hypoglycemia can predict the outcome and indicate the severity of the parasitemia. There are at least three causes, not including treatment with quinine or quinidine: depletion of liver glycogen as a result of decreased oral intake during the first one to three days of illness, before medical attention is obtained; consumption of glucose by the large numbers of parasites in the bloodstream that have a glycolytic (Embden–Meyerhof) pathway but not a Krebs cycle; and the hypoglycemic effects of elevated levels of tumor necrosis factors α and β.1-5

Elyiahu Rubin, M.D.
University of California, Irvine, Long Beach, CA 90822

5 References

1. 1

   Krogstad DJ. Plasmodium species (malaria). In: Mandell GL, Bennett JE, Dolin R, eds. Principles and practice of infectious diseases. 4th ed. New York: Churchill Livingstone, 1995:2419.
   

2. 2

   Krishna S, Waller DW, ter Kuile F, et al. Lactic acidosis and hypoglycaemia in children with severe malaria: pathophysiological and prognostic significance. Trans R Soc Trop Med Hyg 1994;88:67-73
   CrossRef | Web of Science | Medline

3. 3

   Phillips RE, Looareesuwan S, Molyneux ME, Hatz C, Warrell DA. Hypoglycaemia and counterregulatory hormone responses in severe falciparum malaria: treatment with sandostatin. Q J Med 1993;86:233-240
   Web of Science | Medline

4. 4

   White NJ, Warrell DA, Chanthavanich P, et al. Severe hypoglycemia and hyperinsulinemia in falciparum malaria. N Engl J Med 1983;309:61-66
   Full Text | Web of Science | Medline

5. 5

   Taylor TE, Molyneux ME, Wirima JJ, Fletcher KA, Morris K. Blood glucose levels in Malawian children before and during the administration of intravenous quinine for severe falciparum malaria. N Engl J Med 1988;319:1040-1047
   Full Text | Web of Science | Medline

Author/Editor Response

Dr. Service replies:

To the Editor: Drs. Piziak and Cryar have more confidence in the accuracy of blood-glucose monitoring in identifying hypoglycemic disorders than I do. The argument that glucose values obtained with a reflectance meter are adequate for the treatment of IDDM and should therefore be suitable for use in screening for hypoglycemic disorders is specious. In identifying hypoglycemic disorders, the recognition of a range of glycemic states is sufficient, whereas in treating patients with IDDM accuracy is essential. We have had many patients referred for evaluation whose results of blood-glucose monitoring at home have been below 50 mg per deciliter; all these patients have turned out to have normal values when they underwent a 72-hour fast. We use glucose data obtained by trained technicians with a reflectance meter solely as a guide during the 72-hour fast, never as a decision point.

However, I suggest we set aside contention about the accuracy of reflectance meters and emphasize the more important issue these writers raise. If, as Drs. Piziak and Cryar state, many of their patients have neuroglycopenic symptoms, screening based solely on reflectance-meter values for the blood glucose level is inadequate; all those patients deserve comprehensive assessment. Dr. Rubin correctly points out that hypoglycemia may be observed in patients with severe falciparum malaria; the risk of hypoglycemia is compounded by treatment with quinidine or quinine.

F. John Service, M.D.
Mayo Clinic, Rochester, MN 55905