Diagnostic value of parameters of glucose metabolism as screening tests for insulinoma

OBJECTIVE: To analyze the diagnostic value of employing the parameters of glucose metabolism as screening tests for insulinoma. METHODS: Blood glucose profiles within 72 h were recorded by continuous glucose monitoring system (CGMS). Blood samples were collected to detect the HbA1c and GA levels. All subjects received a delayed 75 g oral glucose tolerance test (OGTT) and a simultaneous insulin and C peptide releasing test. RESULTS: Levels of HbA1c [(4.49 +/- 0.63)% vs (5.60 +/- 0.25)%, (5.28 +/- 0.48)%], fasting blood glucose [(3.44 +/- 0.78) mmol/L vs (4.82 +/- 0.35) mmol/L, (4.70 +/- 0.49) mmol/L] and the lowest blood glucose with CGMS [(2.31 +/- 0.24) mmol/L vs (3.28 +/- 0.45) mmol/L, (3.28 +/- 0.99) mmol/L] in insulinoma group were significantly lower than that in impaired glucose tolerance or diabetic patient group and functional hypoglycemia group (P value < 0.05). On the contrary, the levels of IRI (insulin release index) (0.38 +/- 0.07 vs 0.11 +/- 0.06, 0.16 +/- 0.03), CPI (C-peptide index) (0.03 +/- 0.01 vs 0.02 +/- 0.01, 0.02 +/- 0.01) in insulinoma group were higher than those of two other groups (P value < 0.05). Areas of ROC curve were 0.875, 0.955, 0.974, 0.848, 0.916 respectively as screening tests for insulinoma. CONCLUSION: The measurements of HbA1c, fasting blood glucose, IRI, CPI and the lowest blood glucose with CGMS might be useful screening tools to identify insulinoma.