If the primary purpose of the annual visit is to address the status and management of the patient's chronic conditions, such that these are the primary diagnoses on the claim form, you should use the usual office visit codes (assuming the services are provided in the office).
When the blood vessels are this small they are called capillaries. There are more capillaries (and more miles of capillaries) than any other kind of blood vessel. To answer your question, there are approximately 60,000 miles of blood vessels in an adult human body. That's about 100,000 kilometers. And if you really did stretch out your vessels for 60,000 miles most of them would be capillary miles. Each capillary is very short, but there are so very many of them. I found the answer to your question in a college textbook of human anatomy and physiology.
How Many Gallons of Blood are in the Human Body? An average adult human with 160 pounds (72 kilograms) has 1.3 US Gallons of blood in the body. How Many Pints of Blood in the Human Body? An average adult human with 160 pounds has 10.5 Pints of blood in the body. How Much Blood Does an Average Child Have? An average child with a weight of 80 pounds has 2.5 liters of blood (like half of blood from adult human) in the body. How Much Blood Does a Pregnant Woman Have? A woman with a normal-sized fetus with an approximately birth weight of 3.3 kg, may have extra 1.25 liters of blood than non-pregnant woman due to the increase in plasma volume.