Welcome, Tom!

I am a Type 2 diabetic.

Are you on medication?  (Metformin, etc.)  As you run, your body uses sugar (carbs) as fuel to build muscle and keep you going.  Medication can interfere with your body's ability to process carbs, thereby spiking your blood sugar (it happened to me).

All I can say is keep plenty of Gu energy gel for long runs (make sure it contains electrolytes, specifically sodium and potassium).  Also, you might to take along some sugar tablets to ward off hypoglycemia (been there, done that ).

Gu is an energy gel (it'll keep you fueled on long runs):

http://guenergy.com/products/gu-energy-gel

I take cinnamon supplements (they lower blood sugar).  They also contain antioxidants which repair damaged cells (as a result, I don't have any problems with my feet).

I also take Vitamin C and Vitamin B-6 supplements.