Since being a type 1 diabetic she went from 15 pounds to 13 pounds. She is a mix breed of a Silky Terrier and a Yorkie. Her ideal weight is 14 1/2 pounds and need to gain weight. She delveloped type 1 diabetes due to steroids for a skin condition and not due to obesity. We have her on W/D, which she won't eat very often as it has no taste, and plain baked chicken breast or medium rare rib eye steak. Followed with 4 high fiber dog cookies. She has always been a picky eater and we could leave out a plate of food and she would eat a few bites here and there as the day went on. Now we have to give her insulin 2 times a day and she is only to eat 2 times a day right before the shot. SOmetimes she will only eat a few tablespoons of food and then 5 hours later she is barking for food... and we can feed her per doctors orders. Then went it is time to eat you would think she would be ready to eat but nope... she will only eat a about 1/2 pound of food if we are lucky. We have found that with 5 units of insulin and the amput of food she will eat is just not working. When we bump her up to 6 units she will eat more but then her blood surgar will drop about 6 hours later and we have to feed her something to get it in a save range (this is usually at 3 am in the morning!). Whe have tried Oragins (?) 95% meat organic, Blue Buffalo, and few other high end food and she won't touch them. Ughhhhhhh help

Needless to say, that picky eaters make difficult diabetics.
Are you feeding the canned w/d? If so, try heating it. There are other diabetic foods out there that you can try also. Although they may be just unpalatable to her as the next.
Some other things you might try, chicken or beef broth, canned stringbeans, carrots, canned sweet potato. Try to stick to the lo-sodium or sodium free varieties.
They actually won't do much for the weight gain but adding them in to the prescription foods, if she likes them, may entice to here to eat more at a time.
You could boil her chicken and add a little rice in, of course you will want to skim off the fat. The trick is to get her to eat so she can take her insulin safely, and you may have to resort to some unconventional things if she continues to refuse the diabetic foods.
Has she been in for a glucose curve recently to check the overall effectiveness of the dosage and type of insulin? If not, that may be a good thing to consider.
Of course check with your vet before you change it up and remember that these are added fiber which is not necessarily bad for her, but you would want to get the OK of someone who knows her medical history.