HPI:

47 yo M with history of HTN, HLD, morbid obesity presenting via EMS with altered mental status, found to be hypoglycemic with blood glucose in the 30’s prior to arrival.  Patient received two doses of dextrose via EMS enroute, and was still hypoglycemic in the 50s on arrival.  Mental status improving, and the patient says he has had episodes of low blood sugar in the past but never followed up for full medical evaluation.  No known history of diabetes.  Denies any daily meds. No recent illness, changes in diet or prolonged fasting. 

PE:

BP 140/64;  Pulse 114;  Temp 97.7 °F;  Resp 15; SpO2 95%;  Wt 204.1 kg (450 lb); BMI 70

General: morbidly obese, diaphoretic

CV: tachycardia

Resp: mild resp distress when supine, improves when sitting upright

Neuro: mildly confused, but alert and oriented x3. Mild tremor, no seizure activity. No paresthesias.

Hypoglycemia DDx:

• Drugs (insulin/secretagogues)
• Critical illness (sepsis, hepatic, renal or cardiac failure)
• Hormone deficiency (cortisol, glucagon and epinephrine)
• Endogenous hyperinsulinism (insulinoma, insulin autoimmune hypoglycemia, functional beta cell disorders)

Workup/Management:

• Labs: CBC, chem, lactate, C-Peptide, beta-hydroxybutyrate, proinsulin, hypoglycemia panel (sulfonylurea and meglitinide screen)
• Patient was given D10NS bolus and started on D10 drip with persistent hypoglycemia
• Labs showed blood glucose of 29 on initial chem, elevated insulin, proinsulin, c-peptide
• Negative for circulating oral hypoglycemic agent

Given history and lab findings above, insulinoma was suspected and patient underwent CT chest, abdomen and pelvis, which revealed a pancreatic tail mass

• Patient was not a good candidate for surgery given body habitus and comorbidities, and was treated medically with diazoxide

Take home points:

• Hypoglycemia workup is indicated for patients with Whipple Triad:
• Symptoms consistent with hypoglycemia
• Low plasma glucose concentration measured with a precise method (ie. not a home glucose monitor) when symptoms are present
• Relief of those symptoms after the plasma glucose level is raised
• History is KEY! Be sure to ask about timing of symptoms (especially in relation to meals), comorbidities, social history, medication history (patient and household members)

• Plasma insulin, C-peptide, and proinsulin values are elevated in patients with insulinomas, oral hypoglycemic agent-induced hypoglycemia, and insulin autoimmune hypoglycemia. 
• The presence of insulin or insulin receptor antibodies can distinguish insulin autoimmune hypoglycemia from insulinoma.
• Insulinoma is rare, usually solitary and benign
• Definitive treatment is surgical resection of tumor, but can be medically managed with diazoxide or somatostatin analogues (octreotide, lanreotide) to diminish insulin secretion