This one has a reasonably settled answer, so here it is. Quarterly for the first year is convention rather than evidence, and it is defensible for a simple reason: it is roughly the interval over which HbA1c becomes informative again, since it reflects about three months of glycaemia. After the first year, and once doses are stable, annual is reasonable unless something specific is being followed.

Dr.NutriCornell said:

Quarterly for the first year is convention rather than evidence, and it is defensible for a simple reason: it is roughly the interval over which HbA1c…

Agreed, and reference ranges are laboratory-specific. Comparing your number to somebody else's range, or to a screenshot from another country, is how people convince themselves something is wrong.

If somebody has the primary source to hand I would rather cite it than paraphrase it.

marco_milano said:

My prescriber ordered three tests and this board recommends about twenty, and I would like to know which of those two lists is right.

Can confirm the pattern marco_milano describes. A defensible baseline is short: HbA1c and fasting glucose, a lipid panel with ApoB if you can get it, ALT and AST, creatinine with eGFR, TSH, ferritin and B12, and a full blood count. That set catches the things that change, the things that explain symptoms, and the things that alter the prescribing decision. Almost everything else on the long circulating lists is either invariant, uninterpretable without a specific question, or an incidental finding waiting to cause an unnecessary workup.

That is the short version; the long version is somebody else's post.

Clinical perspective, offered as context rather than as advice.

PSA: get baseline labs BEFORE starting baseline bloodwork therapy. You need a "before" picture to measure progress. My recommended pre-treatment panel:

1. CMP + A1C + fasting insulin
2. Complete lipid panel with particle count if possible
3. hsCRP, ferritin, B12, vitamin D
4. Thyroid panel (TSH + free T4)
5. CBC with differential
6. Liver panel (ALT, AST, GGT)
7. DEXA scan or body composition

Total cost at Quest without insurance: ~$200. Worth every penny for the data.