Agree, but it could be caused by low cortisol, that also is common, so I think blood sugar should be tested together with a saliva cortisol test ( more reliable than serum cortisol).
How does fructose get processed- from memory it' s dealt differently in the liver from other sugars and that may explain the effect. Fruit is packaged naturally with fibre to slow down its digestion. Whacking your liver with neat fructose may be more than it can deal with, particularly if there are toxins/ other compounds for liver to deal with at the same time.