Insulin,
proinsulin, and
C-peptide levels increase with sulfonylurea exposure but the acuity of increase has not been described in dialysis patients. We present a case of a dialysis patient who presented with
hypoglycemia and was found to have accidental sulfonylurea ingestion. This is a 73-year-old man with
ESRD on
peritoneal dialysis, without history of diabetes, who presented with
hypoglycemia. Past medical history includes
multiple myeloma,
congestive heart failure, and
hypertension. At initial presentation, his
blood glucose was 47 mg/dL, with concomitant elevations in the following:
C-peptide 30.5 (nl: 0.8-3.5 ng/mL),
insulin 76 (nl: 3-19 μIU/mL), and
proinsulin 83.3 (nl: ≤8.0 pmol/L). During the 72-hour fast, which he completed without
hypoglycemia,
insulin declined to be within normal limits (to 12 μIU/mL);
proinsulin (to 12.1 pmol/L) and
C-peptide (to 7.2 ng/mL) levels decreased but remained elevated. The sulfonylurea screen ultimately returned positive for
glipizide, clinching the diagnosis. This is the first reported case which characterizes the chronic elevation of
proinsulin in a patient with
ESRD, as well as its dramatic increase after a presumed solitary exposure to sulfonylurea. The 72-hour fast conducted gives insight into the clearance of
insulin,
proinsulin, and
C-peptide after sulfonylurea ingestion in
ESRD.