Insulin Autoimmune Syndrome: a rare cause of postprandial hypoglycemia

Abstract

SummaryA 65-year-old obese Caucasian woman presented with symptomatic postprandial hypoglycemic episodes, resolution of symptoms with carbohydrate intake and significantly elevated anti-insulin antibody levels. She did not have any evidence for the use of oral antidiabetic medications, insulin, herbal substances, performing strenuous exercise or history of bariatric surgery. Fingerstick blood glucose readings revealed blood sugar of 35 mg/dL and 48 mg/dL, when she had these symptoms. Her medical history was significant for morbid obesity, hypothyroidism and gastro esophageal reflux disease. Her home medications included levothyroxine, propranolol and omeprazole. A blood sample obtained during the symptoms revealed the following: fingerstick blood sugar 38 mg/dL, venous blood glucose 60 mg/dL (normal (n): 70–99 mg/dL), serum insulin 202 IU/mL (n: <21), proinsulin 31.3 pmol/L (n: <28.9), C-peptide 8 ng/mL (n: 0.9–7), beta-hydroxybutyrate 0.12 mmol/L (n: 0.02–0.27) anti-insulin antibody >45.4 U/mL (n: <0.4). The result obtained while screening for serum sulfonylurea and meglitinides was negative. The repeated episodes of postprandial hypoglycemia associated with significantly elevated anti-insulin antibodies led to a diagnosis of insulin antibody syndrome (IAS). Significant improvement of hypoglycemic symptoms and lower anti-insulin antibody levels (33 U/mL) was noted on nutritional management during the following 6 months. Based on a report of pantoprazole-related IAS cases, her omeprazole was switched to a H2 receptor blocker. She reported only two episodes of hypoglycemia, and anti-insulin antibody levels were significantly lower at 10 U/mL after the following 12-month follow-up.Learning points:Initial assessment of the Whipple criteria is critical to establish the clinical diagnosis of hypoglycemia accurately.Blood sugar monitoring with fingerstick blood glucose method can provide important information during hypoglycemia workup.Autoimmune hypoglycemia is a rare cause of hypoglycemia, which can be diagnosed on high index of clinical suspicion and systematic evaluation.

Hypoglycemia Due to the Presence of Anti-insulin Antibodies: A Case Report

“…This also supports the diagnosis of insulin autoimmune hypoglycemia. In a case report by Pooja and colleagues, neuroglycopenic symptoms in a patient with insulin autoimmune hypoglycemia were observed after 2 h of a meal (2). The drugs containing sulfhydryl groups are known to be associated with insulin autoimmune hypoglycemia (2,6).…”

“…The drugs containing sulfhydryl groups are known to be associated with insulin autoimmune hypoglycemia (2,6). In addition, case reports showing association with alpha lipoic acid (5) and with proton pump inhibitors containing sulfhydryl groups (2)…”

“…There are also publications showing association with other drugs, which most frequently include methimazole, along with others such as D-penicillamine, procainamide, isoniazid, hydralazine, glutathione, captopril, and imipenem (4). In addition, incidences related to alpha lipoic acid (5) and proton pump inhibitor (1,2) have also been reported.…”

A Case of Autoimmune Hypoglycemia in Switzerland

“…The subject described in the present report was taking two drugs that contained active thiol metabolites, namely Pantoprazole and Clopidogrel. There are case reports of IAS in patients using thiol-containing proton pump inhibitors including Pantoprazole and Omeprazole [9,10]. The mechanism of development of IAS with thiol group-containing drug is not entirely clear.…”

Rare Cause of Recurrent Hypoglycemia: Insulin Autoimmune Syndrome

“…The mechanism of endogenous autoantibody induced hypoglycemia is that, after food intake, the endogenous antibodies bind to the secreted insulin and proinsulin(s) causing the insulin to be ineffective and causing postprandial hyperglycemia, consequently increasing insulin release further. The dissociation of insulin from insulin autoantibodies resulted in extremely high levels of unbound insulin and caused hypoglycemia [ 8 , 9 ]. From a previous case report, about 42% had postprandial hypoglycemia, 31% had fasting hypoglycemia, and 24% had both postprandial and fasting hypoglycemia.…”