Objectives To compare hypoglycemic warning symptoms (main objective) and incidence of severe hypoglycemia (secondary objective) between patients treated with animal and human insulin preparations.

Research Design And Methods Two hundred forty-seven patients on treatment with animal insulin preparations and 276 patients on human insulins, matched for duration of diabetes (16 ± 11 vs. 15 ± 10 yr), were recruited for the study. Patients were interviewed with a standardized questionnaire.

Results When asked which symptom usually occurs first during hypoglycemia, 19% of the animal insulin group and 22% of the human insulin group answered “sweating,” 19 and 17%, respectively, answered “trembling,” and 15 and 11%, respectively, answered “unrest.” According to the patients' perception, in both groups, their most reliable hypoglycemic warning symptoms were “trembling” (26 and 22%) and “sweating” (15 and 18%). Six and eight percent of patients, respectively, reported hypoglycemia unawareness and 17 and 18%, respectively, impaired awareness of hypoglycemia. The incidence of severe hypoglycemia was 0.45 cases/patient-yr in patients treated with animal insulins and 0.46 cases/patient-yr in patients treated with human insulin preparations. The differences were not statistically significant.

Conclusions This study shows that hypoglycemic warning symptoms and the incidence of severe hypoglycemia are comparable between patients on treatment with human and animal insulin preparations.