he first step in diagnosing the condition is undergoing a lactulose-mannitol test. You may also hear this test referred to as the PolyetheGlycol Test or PEG. Water-soluble sugar molecules, both mannitol and lactulose, can't be used or metabolized by your body. They differ in size and weight and are absorbed into your bloodstream. The actual rate of absorption varies.
In a healthy digestive process, the cells digest mannitol with ease. On the other hand, the lactulose only digests partially. Therefore, the results of this test should indicate a high level of mannitol and a low level of lactulose for a digestive system that isn't hindered by leaky gut syndrome.