The next time you book bloodwork, ask your doctor to add fasting insulin to the panel. Most do not order it unless you ask.
Fasting glucose and HbA1c are the standard metabolic screens. Both can sit comfortably in range for years while insulin is quietly climbing to keep them there.
That compensation is the story. Your pancreas works harder to hold glucose steady, and the work itself is the early warning.
By the time fasting glucose finally drifts up, insulin resistance has often been building for a decade. The point of checking insulin is to catch the upstream signal instead of waiting on the downstream one.
This shift matters more after fifty. The decline in estrogen across perimenopause and beyond is associated with reduced insulin sensitivity, more visceral fat, and a narrower metabolic margin than you had at forty.
A body of research on postmenopausal metabolism, including work surfaced repeatedly in major endocrinology reviews, treats this trajectory as measurable and modifiable, not inevitable. Seeing it on paper is what makes it modifiable.
Here is the catch on interpretation. Standard lab reference ranges for fasting insulin run wide, sometimes up to twenty-five microIU per milliliter, and there is no settled consensus on a single optimal target.
Many researchers and metabolic-focused clinicians watch for fasting insulin in the single digits as a working signal of preserved sensitivity. Guidelines do not endorse one number, so treat it as a trend you track over time, not a pass-fail score.
The useful tool alongside it is HOMA-IR. The formula is fasting insulin multiplied by fasting glucose in milligrams per deciliter, divided by four hundred and five.
A HOMA-IR near one is generally associated with good insulin sensitivity in research populations, the range between one and two is a grey zone worth watching, and values above two are typically described as insulin resistance worth addressing with training, protein and fiber distribution, sleep, and repeat labs.
Ask for fasting insulin on the same draw as your next lipid and glucose panel, and ask your doctor to calculate HOMA-IR with you. If they push back, ask whether knowing your insulin trajectory before glucose shifts would change how you manage the next ten years.
That is what this number buys you. Not a diagnosis, but a head start.
