The insulin test: negative and positive tests versus numerical values.

Area of Science:

• Gastroenterology
• Surgical Research

Background:

• The insulin test and 2-deoxy-D-glucose (2DG) test are used to assess vagal nerve activity.
• Test results are typically classified as negative or positive based on predefined criteria.

Purpose of the Study:

• To evaluate the reliability of negative versus positive insulin test results in predicting acid response after selective vagotomy and pyloroplasty (SV + PP).
• To determine if specific criteria for the insulin test accurately reflect post-vagotomy acid secretion and the procedure's effectiveness.

Main Methods:

• Compared acid response to insulin and 2DG in 42 male duodenal ulcer patients undergoing SV + PP.
• Analyzed negative and positive insulin test results against varying criteria and their correlation with acid output and reduction percentage.

Main Results:

• Mean acid response to insulin and 2DG was lower in negative tests, with greater reduction post-SV + PP.
• Significant overlap in responses and reductions between negative and positive tests was observed.
• Tests negative to four or more criteria showed minimal stimulated secretion (<0.50 mEq/30 min) but wide reduction variability (60-100%).

Conclusions:

• Single negative or positive insulin test results offer limited predictive value for post-vagotomy acid response or procedure effectiveness.
• Numerical reporting of basal and stimulated acid output and concentration is recommended over binary negative/positive classifications for insulin and 2DG tests.