It could actually be very common. Think about this: What are the main documented risk factors for plantar fasciitis? (see this).
1. High BMI
2. Tight calf muscles

What do those with type 2 diabetes have:
1. High BMI
2. Tight calf muscles (from the glycation of the collagen)

What is a common diagnostic finding in plantar fasciitis: increased thickening of the plantar fascia

What is a common finding in diabetes: increased thickening of the plantar fascia

How many people with diabetes have plantar fasciitis (as they have all the risk factors), but it is masked by the sensory neuropathy?

Do these people with plantar fasciitis rupture and this is a risk factor for midfoot Charcot’s?

For more on latest research and thought on plantar fasciitis, see Podiatry Arena