This Article Full Text Full Text (PDF) Submit a related Letter to the Editor Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Berman, N. Articles by Ipp, E. Search for Related Content PubMed PubMed Citation Articles by Berman, N. Articles by Ipp, E.

Erratic Oscillatory Characteristics of Plasma Insulin Concentrations in Patients with Insulinoma: Mechanism for Unpredictable Hypoglycemia¹

Department of Medicine and Pediatrics, Harbor-University of California Los Angeles Medical Center, Torrance, California 90509; and Lilly Laboratory for Clinical Research, Indianapolis, Indiana

Address all correspondence and requests for reprints to: Nancy Berman, Walter Martin Research Center, Harbor-University of California Los Angeles Medical Center, 1124 West Carson Street, Torrance, California 90502. E-mail: Berman{at}harbor6.humc.edu

Patients with insulin-producing tumors may have hypoglycemic symptoms at unpredictable times. This study evaluated whether plasma insulin oscillations, known to occur in normal individuals but not explored in patients with insulinomas, could be an underlying mechanism for such events. Nine normal subjects and five patients with proven insulinomas were studied in the fasting state. Serial sampling of arterialized blood over 80–100 min, at 2- or 3-min intervals was performed. In normal subjects, mean plasma glucose and insulin concentrations were 5.3 ± 0.1 mmol/L and 58 ± 9 pmol/L, respectively. Regular, low-amplitude plasma insulin oscillations were observed, with a period of 10–17 min. The subjects with insulinomas had lower mean plasma glucose and higher insulin concentrations than controls, 3.6 ± 0.3 mmol/L (P = 0.01) and 150 ± 42 pmol/L (P = 0.01), respectively. They also had insulin oscillations that appeared unstable as a result of variability in duration and amplitude compared with controls. The insulin pulses were irregular, and interpeak intervals varied between 4–54 min in different subjects; in some subjects, the amplitude was also variable, with sudden spontaneous pulses as high as 565 pmol/L, with an associated glucose decrement. We conclude that large spontaneous bursts of insulin secretion occur in patients with insulinomas as part of an erratic pattern of oscillatory insulin secretion, and these can account for unpredictable occurrences of hypoglycemia.

This article has been cited by other articles:

				P. Wiesli, B. Schwegler, B. Schmid, G. A Spinas, and C. Schmid Mini-Mental State Examination is superior to plasma glucose concentrations in monitoring patients with suspected hypoglycaemic disorders during the 72-hour fast Eur. J. Endocrinol., April 1, 2005; 152(4): 605 - 610. [Abstract] [Full Text] [PDF]

				C. S. Mao, N. Berman, and E. Ipp Loss of entrainment of high-frequency plasma insulin oscillations in type 2 diabetes is likely a glucose-specific {beta}-cell defect Am J Physiol Endocrinol Metab, July 1, 2004; 287(1): E50 - E54. [Abstract] [Full Text] [PDF]

				S. Vig, M. Lewis, K. J. Foster, and A. Stacey-Clear Lessons to be learned: a case study approach Insulinoma presenting as a change in personality The Journal of the Royal Society for the Promotion of Health, March 1, 2001; 121(1): 56 - 61. [Abstract] [PDF]