Regularly overindulging in simple, high-GI carbs—the kind that produce the beloved sugar rush—can be dangerous. "There's a lot of evidence that blood glucose spikes are bad for your heart and can raise your risk for type 2 diabetes," says Brand-Miller. "We're beginning to think that type 2 diabetes develops from a process of exhaustion, in which the cells that produce insulin just can't keep up with the high demand, day after day, year after year." Those glucose spikes, says Brand-Miller, are also thought to indirectly cause irritation of the cells lining the blood vessels, which can lead to inflammation and plaque buildup—risk factors for heart disease.
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