Endocrinology and Diabetes Associates, LLC, comprised of Dr. Johnson and Dr. Cowart, provides care for a wide range of endocrine problems for adults 18 years and older. Office Hours. Monday - Thursday: 8 AM to 5 PM; Friday: 8 AM to 12 PM; Phone Numbers. Phone: 256.551.4505; Fax: 256.551.4474; Address. Endocrinology and Diabetes Associates, LLC.