OK, type 2 diabetics, suffering from a mysterious condition that prevents insulin (an endocrine hormone) acting on their cells, can achieve very good blood sugar control by overwhelming the resistance with exogenous insulin.

And yet they still suffer horrible complications. Which look awfully like hypothyroidism.

The simplest explanation is that this mysterious condition is interfering with other endocrine hormones as well.

Desiccated thyroid, containing excessive T3, will overwhelm the hormone resistance, and clear up the complications of diabetes.

T4 alone will not change the amount of T3 in the blood significantly, since it is subject to the body's T4->T3 conversion mechanism, which defends T3 levels.

Therefore T4 will not help diabetics, but T4/T3 combinations will.

Broda Barnes observed this empirically in the sixties. I predicted it independently before I read his book.

Find a diabetic colleague, and explain this to him. I predict that he will suddenly take the idea very seriously indeed.