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Your article says elevated concentrations of glucose in the blood is “a problem that occurs downstream” of impaired response to insulin. Yet artery blockage is defined as a failure of cells to react to insulin. So, would not the problem be upstream of the impairment?

Marry Morel
Prescott, Ariz.

Downstream of the impairment, here, means after—in the biochemical flow—effects first play out. In other words, it’s too late to eliminate the problem with good glucose control because the insulin resistance and its complications predated poor glucose control .—J. Raloff