Type B insulin resistance syndrome is a manifestation of autoantibodies to the insulin receptor that results in severe hyperglycemia and acanthosis nigricans. However, the mechanisms by which these autoantibodies induce hypoglycemia are largely unknown. In this paper, we report the case of patient with type B insulin resistance syndrome who presented with frequent severe fasting hypoglycemia and acanthosis nigricans.
To evaluate the mechanism of hypoglycemia, we measured the inhibition of insulin binding to erythrocytes and IM9 lymphocytes in a sample of the patient's dialyzed serum before and after immunosuppressive therapy.
In the patient's pre-treatment serum IgG, the binding of 125I-insulin to erythrocytes was markedly inhibited in a dose-dependent manner until the cold insulin level reached 10-9 mol/L. We also observed dose-dependent inhibition of insulin binding to IM9 lymphocytes, which reached approximately 82% inhibition and persisted even when diluted 1:20. After treatment with glucocorticoids, insulin-erythrocyte binding activity returned to between 70% and 80% of normal, while the inhibition of insulin-lymphocyte binding was reduced by 17%.
We treated a patient with type B insulin resistance syndrome showing recurrent fasting hypoglycemia with steroids and azathioprine. We characterized the patient's insulin receptor antibodies by measuring the inhibition of insulin binding.
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There have been no systematic observations regarding changes in early phase insulin secretion among Korean prediabetes and early stage type 2 diabetes mellitus (T2DM) patients.
We conducted 75-g oral glucose tolerance tests (OGTT) in 873 subjects with suspected abnormal glucose tolerance. All subjects were diagnosed as having normal glucose tolerance (NGT), prediabetes (preDM), or T2DM according to the OGTT results and the insulin secretory and insulin resistance indices of each subject were calculated. Additionally, we analyzed the changes in early phase insulin secretion according to changes in fasting (Glc0), post-prandial (Glc120) glucose and HbA1c (A1c) levels.
As compared to subjects with NGT, the insulin secretory indices of the preDM and T2DM subjects progressively declined, and the insulin resistance indices were progressively aggravated. Early phase insulin secretion decreased rapidly according to the increments of Glc0, Glc120 and A1c, and these changes were most prominent in the NGT stage. Compared to the control group, the early phase insulin secretion levels of the preDM or T2DM subjects were less than 50% when Glc0 was over 100 mg/dL, Glc120 was over 145 mg/dL, and A1c was over 5.8%.
This study suggests that progressive beta cell dysfunction in Koreans may be initiated and rapidly aggravated during the period generally designated as 'normal.'
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