Pravachol (pravastin sodium) does not ALWAYS cause diabetes. The drug, however has a number of possible serious side affects. A discussion of these may be found on the United States government website for the FDA (Food and Drug Administration). Go to their site and type in "pravachol" on their internal document search engine.
I am not familiar with this drug. Is it a statin drug?
If so, these drugs are known to cause diabetes / worsen blood sugar control in persons already having diabetes.