Losartan Induced Hypoglycemia in the Absence of Diabetes Mellitus - a Concealed Diagnosis

Background: Losartan has been shown to attenuate symptomatic and hormonal responses to hypoglycemia in prior studies. This results predominantly from blocking AT-II receptors blunting the hypoglycemia-induced rise in plasma epinephrine predisposing them to hypoglycemia unawareness. To our knowledge, however there are no case reports describing losartan induced hypoglycemia in a nondiabetic patient. This abstract is the first description of a patient without diabetes mellitus experiencing severe hypoglycemia induced by the ARB, Losartan. Clinical Case: A 51- year old nondiabetic female was found to be somnolent and in acute respiratory failure. Blood sugar was 34 mg/dL. She received D10 by EMS while coming to the hospital. She was intubated and treated for atypical pneumonia based on bilateral interstitial infiltrates. She remained persistently hypoglycemic around 62 mg/dL. Her most recent A1c was 4.4%. Thyroid function was within normal limits. AM cortisol was 16.8 mcg/dL so there was no concern of adrenal insufficiency. She had no history of gastric bypass surgery. She underwent a 72-hour fast and developed symptomatic hypoglycemia. Her venous blood glucose at this time was 49 mg/dL. Her hypoglycemia panel obtained at this time showed C-peptide 0.7 ng/mL, total insulin 2.9 microU/mL, proinsulin 3.1 pmol/L, IGF 45 ng/mL and BHOB 13.5 mmol/L. Her oral hypoglycemic agent screen was negative. Based on levels that were obtained during the hypoglycemic episode, this correlated to a non-diagnostic study for conventionally described causes of hypoglycemia including exogenous insulin, insulinoma, NIPHS, PGBH, oral hypoglycemic agent, insulin autoimmune or IGF-mediated. Her medication list was analyzed again. We learnt that she had recently been started on losartan about a month prior to this admission for her heart failure management. On further review, the patient mentioned that she was noticing these hypoglycemic events in the last month and that seemed to coincide with when she was started on losartan. We subsequently held losartan which resulted in profound improvement in her glycemic control and her blood sugars improved to a range of 110–140 mg/dL consistently. She was discharged from hospital off losartan. Blood sugar was stable on repeat testing outpatient after discharge. Conclusion: This is the first case that demonstrates the role of losartan in causing severe hypoglycemia in patients without a history of diabetes mellitus. Discontinuation of losartan resulted in prompt improvement of hypoglycemia. Reference: (1) Deininger E, Oltmanns KM, Wellhoener P, Fruehwald-Schultes B, Kern W, Heuer B, Dominiak P, Born J, Fehm HL, Peters A. Losartan attenuates symptomatic and hormonal responses to hypoglycemia in humans. Clin Pharmacol Ther. 2001 Oct;70(4):362–9. PMID: 11673752.