SandraNC_45 said:

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…

That is correct as far as it goes, and here is where it stops going. The single most useful discipline is bringing the whole panel to a clinician rather than one flagged value. One out-of-range result in isolation generates anxiety and unnecessary tests; the same result next to the trend and the rest of the panel usually generates a shrug.

I would rather be corrected than agreed with, if it comes to it.

SandraNC_45 said:

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…

Pushing back on SandraNC_45 here. I would drop the "get everything" instinct further than this thread does. Every extra test is another chance at a false positive, and incidental findings have their own cost in scans, biopsies and worry.

Taking the question as asked, rather than the general version of it. 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.NateNeph said:

The single most useful discipline is bringing the whole panel to a clinician rather than one flagged value.

Same pattern here, and in the same order. The detail I would add is minor and it is already implied above.