Munchausen syndrome with factitious hypoglycemia due to deliberate insulin analog administration and factitious hyperglycemia in a patient with hypothyroidism.

Background: Hypoglycemic syndrome is a potentially life-threatening condition that can lead to the disruption of brain and internal organ functions, and in severe cases to irreparable consequences or death. Factitious hypoglycemia (FH) is the deliberate use of insulin preparations or oral hypoglycemic drugs with the aim of lowering blood glucose levels into the pathologically-hypoglycemic range. Deliberate administration of insulin analogs may be difficult to prove because they might not have epitopes or containing low affinity epitopes that are the targets of antibodies used in particular assay kits.

Case presentation: A 34 years old woman was admitted to the Endocrinology Research Centre in September 2021 with a diagnosis of hypothyroidism and diabetes mellitus. Upon admission she complained of high glycemia indexes up to a maximum of 34 mmol/l ( 612 mg/dl), high TSH and low free T4 ( fT4) concentrations, despite reporting regular levothyroxine administration at a dose of 200 mcg per day. Under nursing supervision, her fT4 was rapidly normalized suggesting non-compliance as the cause of low thyroid hormone milieu. Glycemic fluctuations from 33 to 2.1 mmol/l (594 to 38 mg/dl) according to glucometer measurements were observed against the background of Lis-Pro insulin therapy, while no hyperglycemia was registered in venous blood and in the interstitial fluid concomitantly with the values found by glucometer. It was assumed that the patient's fingers were intentionally contaminated with glucose solution. Factitious hypo- and hyperglycemia were suspected. During yet another episode of hypoglycemia (1.86 mmol/L, 33 mg/dl) venous blood was drawn. Low to low-normal insulin and C-peptide values were found: 2.2 µU/ml (Roche kit) and 1.18 ng/ml, respectively. Therefore, insulin concentration in the same sample was re-tested with another kit (Abbott) and a significantly elevated value of 89.9 µU/ml was detected. Based on these results, FH was confirmed due to exogenous administration of an insulin analog undetectable by the Roche kit.

Conclusion: This clinical example illustrates to draw attention to multiple manipulations employed by subjects with Munchhausen Syndrome. In addition, this diagnosis may be further complicated by the laboratory use of immunoassay kits incapable of detecting some insulin analogs.