The research I performed on this topic indicates that no known relationship between plantar fasciitis and diabetes has ever been established.  In fact, plantar fasciitis occurs when a long fibrous plantar fascia ligament along the bottom of the foot develops tears in tissue resulting in pain and inflammation.  Some of the signs and symptoms of plantar fasciitis are burning, stabbing, or aching pain in the heel of the foot.  The most common cause for plantar fasciitis is an overload of physical activity or exercise.  This is commonly seen in athletes who change or increase the difficulty of their exercise.  Another cause of plantar fasciitis is arthritis, which makes the elderly women more prone to this condition.  Also, wearing incorrect shoe sizes can cause tears in the tissue.  Contributing factors include people with high arches, flat feet, and obesity.  Diabetes could be a contributing factor with further heel pain and damage, but mostly among the elderly.  The current treatment options for plantar fasciitis are changing physical activities, resting the foot, and applying ice.  Orthotics can be helpful to promote healing and may be able to reverse it in some cases.  

I hope that helps!