How CGM Data Changed the Way I Coach Carb Counting

Carb counting used to be an open-loop exercise: estimate the carbs, take the dose, hope. The continuous glucose monitor closed the loop, and it changed how I coach.

Now I can sit with a patient and read the trace from last night's dinner. A sharp early spike that crashes tells me the insulin timing was off. A slow, grinding rise hours later points at the fat and protein in a takeaway, or a carb count that was quietly underestimated.

Time-in-range — the share of the day spent in target — became my favourite single number, because it reflects the whole day's eating rather than one fasting reading that hides everything that happened after breakfast.

My sports-nutrition background turns out to matter here: I spent years reading how fuelling moved performance, and reading a glucose curve is the same skill aimed at a different goal. The data does not replace the dietitian — it makes the advice specific.

Which monitor produces data worth coaching from is its own decision, and I work through it in my dietitian's guide to CGMs and glucose monitoring.