Could be, but to me it’s at best a ‘never say never’ deal - impossible to prove that’s not the case, but still extremely doubtful, IMO. If he was Type 1, then it would be easily believeable, but for Type 2s only taking Metformin, it’s essentially ‘not a thing.’
It looks to me like he had not fasted before, then slammed right into 5 days of it. It wasn’t the fasting that messed him up, it was when he started eating again - he had soup and took a chlorophyll supplement. He was used to taking the chlorophyll, but perhaps not with such an empty system as after 5 days of fasting, and it’s a known side effect of chlorophyll supplements that they can cause nausea and vomiting.
So, he feels sick, vomits, gets dehydrated, feels dizzy and passes out, hits his head. I wish they had tested him for blood ketone levels - that would be illuminating. The report says, “As acid anions, beta-hydroxybutyrate and acetoacetate can result in a decreased blood pH (acidemia), if present in higher levels.” Okay, so tell us what the ketone level was. All I see is them saying his urine was “2+ ketones.” Sheesh…
In his case, though I’m no kind of a doctor, I’d tell him to forgo the chlorophyll when breaking a fast, probably ease into fasting, i.e. try 1 day then 2 then 3… and consider stopping the Metformin when not eating, or reduce the dose - he ought to run it by his doctor - and stay hydrated.