Even with diabetes... Although this is not strictly a &quot;diet&quot; issue, for years, many doctors tried to strictly control blood sugar levels in their patients.  Variations were frowned up.<p>Turns out, research has now shown that such &quot;overmanaged&quot; patients actually fare worse than those who allow some flexibility in glucose levels.<p>I have a quite knowledgeable family member who has diabetes, from whom I&#x27;ve learned this.<p>As I&#x27;ve gotten older, I&#x27;ve watched a lot of... um, &quot;best practices&quot;, in health care as in other matters, be debunked.  And, in retrospect, the advice often was a matter of self-reinforcing <i>opinion</i> rather than demonstrated science and research results.