To analyze the clinical features of type 2 diabetic patients with insulin autoimmune syndrome after treatment with exogenous insulin.

A total of 106 patients with type 2 diabetes diagnosed with exogenous insulin-related insulin autoimmune syndrome (EIAS) were included from September 2017 to March 2019 in the Department of Endocrinology, Zhongshan Hospital, Fudan University. The clinical data, physical examination, and laboratory examination results of patients were collected.

Of the 106 patients, 84 (79.24%) used premixed human insulin or premixed insulin analogs, and 18 patients (16.98%) presented recurrent hypoglycemia. The arginine stimulation test showed that the median value of the baseline insulin was 73.40 (23.07-146.75) μU/ml, and the median ratio of 4 minute insulin to 0 minute insulin was 1.27 (1.03-1.85), with the mean of the ratio 1.72±1.47. The ratio of baseline insulin (μU/ml) to C-peptide (ng/ml) was 44.60 (14.92-87.93), with an average of 81.92±130.93. Taking the two-fold upper limit of fasting insulin reference value (49.8 μU/ml) as the cut-off point, the subjects were divided into insulin accumulation group (baseline insulin≥49.8 μU/ml) and insulin non-accumulation group (baseline insulin <49.8 μU/ml). Among the 66 patients in the insulin accumulation group, 14 patients had hypoglycemia (21.21%) and 4 patients in the insulin non-accumulation group presented hypoglycemia (10%). The ratio of 4 minute insulin to baseline insulin, ratio of baseline insulin to C-peptide, blood glucose level standard deviation (SDBG) and maximum blood glucose fluctuation amplitude (LAGE) in the insulin accumulation group were significantly higher than those in the insulin non-accumulation group (all P<0.05). Among 66 patients in the insulin accumulation group, 36 patients changed the type of insulin preparafion (insulin treatment group), 30 patients were changed from insulin to oral hypoglycemic agents (oral medication group). After treatment, both SDBG and LAGE in the two groups were significantly lower than before treatment (P<0.05).

With the aggravation of exogenous insulin accumulation, the fluctuation of blood glucose and the proportion of hypoglycemia were significantly increased. There was a characteristic change in islet function in patients with insulin autoimmune syndrome. After arginine stimulation, there was no significant peak of insulin secretion, showing a " high-level" curve. The baseline insulin/C-peptide ratio was significantly increased. The prognosis of EIAS patients is good after timely diagnosis and adjustment of treatment.

Diabetes mellitus, type 2; Insulin autoantibody; Exogenous insulin-related insulin autoimmune syndrome