Scientific article

Hypoglycaemia caused by atypical insulin antibodies in a patient with benign monoclonal gammopathy

Published inJournal of internal medicine, vol. 234, no. 4, p. 421-427
Publication date1993

We describe a 48-year-old woman with recurrent severe hypoglycaemia apparently caused by a paraprotein with insulin-binding capacity. Very high fasting values were found for serum insulin (170 and > 250 mU l-1) as well as for proinsulin 125 pmol l-1 and an insulinoma was suspected. Hypoglycaemia developed after an oral glucose tolerance (OGTT) test but not during fasting for 48 h. Free insulin and C-peptide were normal during OGTT whereas serum insulin was very high. 125I-insulin binding to serum, determined with a polyethylene glycol (PEG) precipitation method was high (40%), and equally high after addition of 1.7 x 10(-5) mol l-1 cold insulin to estimate non-specific binding. By adding very high concentrations of cold insulin, displacement of 125I-insulin bound to serum was found (50% displacement at 4 x 10(-5) mol l-1). No immunoglobulin G (IgG) insulin antibodies were detected by radioimmunoelectrophoresis. On agarose electrophoresis a small paraprotein (4 g l-1) in the gamma-globulin fraction was detected. 125I-insulin binding to this paraprotein was demonstrated. We conclude that if insulin autoantibodies are suspected as a cause of hypoglycaemia screening for insulin antibodies should always be done with a PEG-precipitation method.

  • Autoantibodies/ blood
  • Female
  • Humans
  • Hypoglycemia/ immunology
  • Insulin/blood
  • Insulin Antibodies/ blood
  • Middle Aged
  • Monoclonal Gammopathy of Undetermined Significance/ complications/immunology
Citation (ISO format)
ARNQVIST, H. J. et al. Hypoglycaemia caused by atypical insulin antibodies in a patient with benign monoclonal gammopathy. In: Journal of internal medicine, 1993, vol. 234, n° 4, p. 421–427. doi: 10.1111/j.1365-2796.1993.tb00766.x
ISSN of the journal0954-6820

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