Insulin & C-peptide levels in sulfonylurea-induced hypoglycemia: a systematic review

We will describe insulin and C-peptide levels observed in sulfonylurea-induced hypoglycemia and determine whether these levels differed if obtained before or after hypoglycemic therapy.

We performed a systematic review of the English literature to identify Medline articles containing "sets" (glucose <60 mg/dL with insulin and C-peptide levels). These "sets" were categorized as being obtained BEFORE, AFTER, or UNKNOWN with respect to hypoglycemic therapy.

22 articles, 76 patients, and 97 "sets" were included. Mean glucose (mg/dL), insulin (muIU/mL), and C-peptide (ng/mL) for all "sets' were 28.6 (+/-12.6; 26.1 to 31.2), 54.4 (+/-126.3; 28.3 to 80.5), 7.2 (+/-6.2; 5.9 to 8.5). The BEFORE measures were 24.3 (+/-7.3; 18.7 to 30.0), 36.6 (+/-26.2; 16.5 to 56.7), 5.4 (+/-4.6; 1.5 to 9.2). The AFTER measures were 33.1 (+/-9.8; 28.2 to 38.0), 126.7 (+/-278.1; 0 to 265.0), 10.3 (+/-10.5; 5.1 to 15.4). The UNKNOWN measures were 28.0 (+/-13.5; 24.7 to 31.3), 37.1 (+/-21.8; 31.7 to 42.5), 6.5 (+/-4.3; 5.4 to 7.6). Only one "set" (glucose 49 mg/dL) had insulin <3.9 muIU/mL and C-peptide <1.4 ng/mL.

Insulin > or =3.9 muIU/mL, C-peptide > or =1.4 ng/mL, and glucose <49 mg/dl are consistent with sulfonylurea-induced hypoglycemia. BEFORE levels were lower, but they were consistent with sulfonylurea-induced hypoglycemia.