Allison Herries, RDN, is a registered dietitian for a telehealth company. In her role, she provides nutrition education and counseling to help her clients set and reach their personal health goals.

A 25-hydroxyvitamin D test checks if your body has too much or too little vitamin D. The test involves a simple blood draw, and you don't need to fast beforehand. Risks from the test are rare but ...

A fasting blood sugar test result under 99 mg/dL is considered normal, while 126 mg/dL or higher confirms diabetes. The A1C test measures your average blood sugar over two to three months, with 6.5% ...