[Effect of continuous subcutaneous insulin infusion on the evaluation of β cell function]

To evaluate the impact of continuous subcutaneous insulin infusion (CSII) on β-cell function assessment.

One hundred and twenty-five patients with type 2 diabetes (T2DM) admitted to Third Affiliated Hospital of Sun Yat-sen University treated with CSII were enrolled from May to December 2015. Blood samples were collected to measure their fasting blood glucose, haemoglobin A1c, blood lipids and plasma C peptide levels (fasting, 30 min and 120 min after a mixed meal) on the next day of their admission before CSII started. When patients achieved the target of fasting capillary glucose ≤ 7.0 mmol/L, C-peptide levels (0 min, 30 min and 120 min after a mixed meal) were measured. Then CSII were stopped at 10 pm with the same tests repeated on the next day.

Compared with those measured before CSII [0 min: (0.35±0.20) nmol/L, 30 min: (0.57±0.31) nmol/L, 120 min: (0.84±0.54) nmol/L], C-peptide levels after stopping CSII at all time points [0 min: (0.41±0.16) nmol/L, 30 min: (0.71±0.33) nmol/L, 120 min: (1.37±0.75) nmol/L] increased (P=0.015, P=0.005, P<0.001) even glucose control was achieved, but significantly decreased immediately before CSII was stopped [0 min: (0.23±0.13)nmol/L, 30 min: (0.39±0.26) nmol/L, 120 min: (0.67± 0.50) nmol/L] (P<0.001, P<0.001, P=0.023). The C-peptide after stopping CSII increased to 141% (0 min), 127% (30 min) and 219% (120 min) respectively compared to those before stopping CSII.

CSII therapy should be stopped for accurate evaluation of β-cell function due to its"β-cell rest"effect in T2DM.