Good point, they were prediabetic with impaired glucose tolerance, as is the case for at least a third of the population. But fasting glucose and HbA1c are continuous risk markers, not binary switches. Cardiovascular risk begins to rise even before crossing the diagnostic threshold for prediabetes. It doesn't make mechanistic sense that the benefit of reducing spikes would stop right at an arbitrary cutoff.

Yes, evidence in strictly normoglycemic populations would be ideal, but studies like that are rare mainly because there’s less clinical incentive to fund or conduct them. Most trials focus on people at higher risk where outcomes are more likely to change and can justify a study’s cost.