Sean,
Diabetics in advanced stages usually go bald. Insulin-resistance, where the body builds up a tolerance for insulin, sees the body make MORE insulin than necessary. The body, for whatever reason, seems to think it needs MORE testosterone to deal with the extra insulin, and the adrenal glands, located above your kidneys, pump out more testosterone and the body also makes less GLOBULIN.
Globulin is often called SBHG, for 'sex-binding-hormone-globulin' because it binds with free testosterone and "carries" it around the body in an unusable form for the alpha five reductase enzymes. There is less "free" testoterone for conversion to DHT. Get it? So, if by eating foods with a low glycemic index, and having a splash of vinegar, or some pickles before a meal with a high glycemic index, you might be able to make a little less testosterone and up globulin at the same time.
Other dietary measures good for hair are soy isoflavons (less androgen receptor production and if you make equol, a sort of natural propecia), green tea extract (inhibits type one to an extent, anti-androgenic effects of a vague nature), eat less saturated animal fat (go for the skim milk, and leaner cuts of red meat because fats from these sources proboably get the liver to synthesize a little more alpha five reductase type two).
Thats about it with diet and baldness.