Blood Sugar Doesn't Tell the Whole Story
Many people assume that if their fasting glucose and A1c are normal, their metabolism is healthy. But blood sugar can stay normal for years while your body works harder and harder behind the scenes to keep it there.
That's where fasting insulin comes in.
What Fasting Insulin Shows
Insulin is the hormone that moves sugar from your blood into your cells. When cells stop responding well to insulin—called insulin resistance—your pancreas compensates by producing more of it.
In the early stages, this extra insulin keeps blood sugar normal. So someone can have:
- Normal fasting glucose
- Normal A1c
- But high fasting insulin, signaling insulin resistance
Over time, if the pancreas can't keep up, blood sugar starts to rise—leading to prediabetes and type 2 diabetes.
Why It Matters
Insulin resistance is linked to:
- Higher risk of type 2 diabetes
- Fatty liver disease
- High triglycerides and low HDL cholesterol
- High blood pressure
- Weight gain, especially around the belly
- PCOS in women and low testosterone in men
How Is It Interpreted?
There's no universal "optimal" cutoff, and lab reference ranges are often wide. Many clinicians consider fasting insulin levels in the low single digits (µIU/mL) to reflect good insulin sensitivity, with higher levels suggesting increasing resistance.
Providers may also calculate HOMA-IR, a score that combines fasting insulin and glucose to estimate insulin resistance.
How to Improve Insulin Sensitivity
- Move regularly: Both strength training and aerobic exercise help muscles use glucose
- Walk after meals: Even 10–15 minutes can blunt blood sugar spikes
- Lose excess weight, especially belly fat
- Prioritize protein and fiber, and limit refined carbs and sugary drinks
- Sleep well: Even a few nights of poor sleep can reduce insulin sensitivity
- Manage stress
Get Tested
Fasting insulin is easy to add to routine blood work and can give you an early warning—while there's plenty of time to make changes.
Learn more about lab testing here: Heva Lab Testing
The Bottom Line
Fasting insulin can reveal insulin resistance years before blood sugar becomes abnormal. Catching it early gives you the best chance to protect your long-term metabolic health.