Correlation Between Capillary and Venous Blood Glucose in the Lactose Tolerance Test

Area of Science:

• Clinical Biochemistry
• Gastroenterology
• Diagnostic Accuracy

Background:

• The lactose tolerance test is a standard method for diagnosing lactose malabsorption.
• Current methodologies lack standardization, leading to inconsistent results.

Purpose of the Study:

• To evaluate the agreement between capillary and venous blood glucose measurements during the lactose tolerance test.
• To determine if capillary blood glucose accurately reflects venous blood glucose levels in this context.

Main Methods:

• A prospective study involving patients with suspected lactose malabsorption.
• Simultaneous venous and capillary blood glucose measurements were taken after a 50g lactose load.
• Agreement was assessed using concordance correlation coefficient, Bland-Altman plots, and Kappa index.

Main Results:

• Eighty-four patients were analyzed.
• Very poor agreement was found between capillary and venous measurements (concordance correlation coefficients ranging from 0.68 to 0.77).
• Capillary measurements consistently yielded higher glucose levels than venous measurements, with low overall agreement (Kappa index 0.59).

Conclusions:

• Venous and capillary blood glucose measurements during the lactose tolerance test are not interchangeable.
• The diagnostic accuracy of the lactose tolerance test may be overestimated due to unstandardized blood sampling methods.
• Future studies must specify whether venous or capillary blood was used for glucose analysis.