Insulin resistance is remarkably common, and it often develops quietly, showing up in ways that don’t look like a typical metabolic problem at all. Here are four subtle signs worth knowing, along with how to actually confirm whether insulin resistance is present rather than guessing from symptoms alone. (Based on the insights of Dr. Suneel Dhand)
Key Takeaways
- Acanthosis nigricans (dark, thickened skin patches) and skin tags have real, well-established links to insulin resistance — general rashes and eczema are more loosely connected.
- Post-meal energy crashes and carb cravings reflect the glucose-insulin spike-and-crash cycle that’s characteristic of insulin resistance.
- Waist circumference specifically reflects visceral fat, which is particularly linked to insulin resistance, beyond overall body fat percentage.
- Fasting insulin combined with fasting glucose (used to calculate HOMA-IR) gives more direct insight than fasting glucose or HbA1c alone.
- A HOMA-IR near 1 generally reflects healthy insulin sensitivity, while values approaching or exceeding 2 are commonly used as an insulin resistance indicator, though cutoffs vary by lab and population.
How Common Is This, Really?
Estimates of insulin resistance prevalence vary considerably depending on how it’s measured and defined, and some estimates for the broader population (including milder, subclinical degrees of insulin resistance) run quite high. Widely cited US data on prediabetes and metabolic syndrome specifically tends to fall in the range of roughly one-third to just under half of adults, which is itself a substantial and often underappreciated number. Regardless of the exact percentage, the broader point holds: this is common enough that it’s worth understanding the signs, rather than assuming it only applies to people who are visibly overweight or already diagnosed with prediabetes.
Sign #4: Recurring Skin Changes
Skin can reflect internal inflammation, and insulin resistance is closely tied to inflammation throughout the body. Two skin findings have real, well-established associations with insulin resistance specifically: acanthosis nigricans (dark, thickened patches of skin, often at the neck, armpits, or other skin folds, though it can occur in people with any skin tone) and skin tags, which appear more frequently in people with insulin resistance and are sometimes removed cosmetically without addressing the underlying metabolic picture. General rashes and eczema are mentioned here too, though it’s worth noting these have a less firmly established, more general connection to insulin resistance compared to the two signs above — eczema in particular is more commonly understood as an atopic/allergic skin condition with its own distinct causes, so it’s a less reliable individual signal on its own.
Sign #3: Wild Energy Swings During the Day
This happens through a fairly well-understood mechanism: consuming excess refined carbohydrates and sugar causes a glucose spike, followed by an insulin spike as your pancreas works to bring glucose back down. Insulin itself is a pro-inflammatory, fat-storage hormone, and the resulting swing often produces an energy crash a couple of hours after eating, along with cravings (especially for more carbohydrates) and a tendency to feel sleepy after meals. Repeated cycles of this pattern throughout the day can be a meaningful sign of underlying insulin resistance.
Sign #2: Excess Body Fat and Waist Circumference
Body fat isn’t just stored energy — it’s metabolically active tissue that produces inflammatory signals, which is part of why body fat percentage and waist circumference are both relevant here. General reference points sometimes cited are under roughly 25% body fat for women and under roughly 15% for men, though individual targets vary and these numbers are reasonably debated; women naturally tend to run higher than men. Waist circumference is a useful complementary measurement, since it more specifically reflects visceral fat around the organs, which is particularly linked to insulin resistance.
Sign #1: Difficulty Concentrating and Mood Swings
Insulin resistance-related inflammation isn’t limited to organs below the neck — it can affect the brain too, and this is a genuine, growing area of research connecting insulin signaling to cognitive function and mood regulation. Some research has found that when people successfully reverse insulin resistance, they report meaningful improvements in mood, stress perception, and concentration. This is an active, evolving research area rather than a fully settled diagnostic sign, but it’s a reasonable pattern to be aware of.
How to Actually Confirm Insulin Resistance
Standard tests like fasting glucose and HbA1c are useful, but a fasting insulin level, drawn at the same time as fasting glucose, gives more direct information. From these two values, you can calculate HOMA-IR (a formula available through several online calculators). A HOMA-IR close to 1 generally reflects healthy insulin sensitivity, while values climbing toward 2 or higher are commonly used as an indicator of insulin resistance, though exact cutoffs vary somewhat depending on the reference population and lab used.
What Actually Helps
Addressing insulin resistance generally comes down to sustained lifestyle change: reducing refined carbohydrates and added sugar, increasing physical activity, prioritizing sleep, and managing stress. Many people notice meaningful improvement within a few weeks of consistent change, though full reversal takes longer and requires ongoing effort. Having a supportive environment — people around you who share similar health habits — genuinely makes this process easier to sustain.
Frequently Asked Questions
Does having eczema or regular rashes mean I have insulin resistance?
Not necessarily — this connection is less firmly established than for acanthosis nigricans or skin tags specifically. Eczema is generally understood as an atopic/allergic condition with its own distinct causes, so it’s a less reliable individual signal on its own.
What’s the best test to actually confirm insulin resistance?
A fasting insulin level drawn alongside fasting glucose, used to calculate HOMA-IR, gives more direct information than fasting glucose or HbA1c alone, which are useful but less specific.
Can insulin resistance really affect mood and concentration?
This is a genuine, growing area of research connecting insulin resistance-related inflammation to brain function. It’s an active, evolving field rather than a fully settled diagnostic sign, but a reasonable pattern worth being aware of.
How is insulin resistance actually treated?
Sustained lifestyle change — reducing refined carbs and sugar, increasing activity, prioritizing sleep, and managing stress — is the core, evidence-supported approach. Many people notice improvement within a few weeks, though full reversal takes longer.
Quick Start Checklist
- ☐ Check for acanthosis nigricans or skin tags
- ☐ Notice patterns of post-meal energy crashes or carb cravings
- ☐ Measure your waist circumference, not just overall weight
- ☐ Ask your doctor for a fasting insulin test alongside fasting glucose
- ☐ Calculate your HOMA-IR once you have both values
- ☐ Focus on reducing refined carbs/sugar, increasing activity, and improving sleep
Disclaimer: This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Prevalence estimates for insulin resistance vary considerably by definition and measurement method; consult your doctor for testing (including fasting insulin and HOMA-IR) rather than relying on symptoms alone. Consult your doctor before making significant changes to diet or activity, especially if you have diabetes or another existing condition.