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This could make sense: caffeine is a "universal" stimulant in that cAMP (which it boosts by blocking degradation) is involved in so many systems in the body as a "secondary messenger". In the brain it stimulates every single neurotransmitter simultaneously by letting each neurotransmitter receptor activation to continue to "ring on" after the normal impulse. The fact it kicks up every neurotransmitter is why it's a stimulant and it's also why too much just makes you jittery: neurotransmitters tend to work in opposing pairs of stimulation and suppression so amping up both at the same time eventually just leads to a energetic but counterproductive "clench".

In the case of the Kreb's cycle it stimulates the breakdown of liver starch into blood glucose. It specifically interacts in opposition to insulin. There are probably two ways this might be problematic. One is what is implied by the work mentioned: raising blood glucose requires higher insulin levels just to keep up which may eventually exhaust the pancreas.

The second pathway not mentioned is an adaptive control system effect: caffeine could "teach" an adaptive control system that normal insulin-mediated glucose control system isn't needed or effective in its normal biological mode due to the lack of control system response to that system - the levels are more controlled by the caffeine mediation than the insulin mediation. This "teaching" is not a anthropomorphic effect but simply a mechanistic feature of higher order adaptive control systems.

I'd be loath to give up my caffeine however without some substitute being available. Also an interesting tidbit: Viagara is an analog to Caffeine in that it works by an exactly equivalent action acting upon gAMP which is a chemical analog to cAMP.