ANSWER:
I would advise you to discuss the issue you wrote about with your father's doctor as well as using the information I've found for you. Johns Hopkins recommends in the article below (see link) that you "give yourself injections in the abdomen (though not within two inches of your navel); the outsides of your upper arms, upper thighs, and hips; and the buttocks." The links below give additional information about various sites for insulin injections and why you should rotate sites. Hope this helps!
http://www.johnshopkinshealthalerts.com/alerts/diabetes/JohnsHopkinsHealthAlertsDiabetes_949-1.htmlhttp://www.diabetesselfmanagement.com/Articles/Diabetes-Definitions/injection_site_rotation/Here's more information about diabetes
http://www.diabetes-guide.org/forumshttp://www.diabetes-guide.org