Expert Q&A

Does anyone have a normal A1C, but high insulin while doing intermittent fasting

Understanding Normal A1C With Elevated Insulin

Many people in their late 40s and early 50s following intermittent fasting report a puzzling lab result: normal A1C levels alongside elevated fasting insulin. This pattern often signals early insulin resistance, where your pancreas produces extra insulin to keep blood glucose in check. Your A1C may read 5.4% or below, yet fasting insulin could sit at 12–18 μU/mL when optimal is under 10. This mismatch is common during perimenopause when shifting estrogen and cortisol disrupt metabolic signals.

In my approach outlined in The CFP Weight Loss Method, we view this as a warning sign rather than failure. Normal A1C reflects average glucose over three months, but it misses the daily insulin spikes that promote fat storage, especially around the midsection. For those managing diabetes risk and blood pressure, catching this early prevents progression to prediabetes.

Why Intermittent Fasting Can Reveal or Worsen This Pattern

Intermittent fasting improves insulin sensitivity for many, but for complete beginners with prior diet failures and joint pain, an aggressive 16/8 or 18/6 window can backfire. Extended fasts may raise cortisol, prompting your body to release stored sugar and demand more insulin. Hormonal changes in midlife amplify this, making weight loss feel impossible despite disciplined eating.

Key triggers include eating too many refined carbs in your window, chronic stress, and poor sleep. If you're overwhelmed by conflicting nutrition advice, focus on this: pair fasting with meals that stabilize blood sugar. Aim for 25–35 grams of protein and 8–10 grams of fiber per meal to blunt insulin response. This strategy has helped hundreds in our program lower fasting insulin by 30–40% within 90 days without extreme restriction.

Practical Steps to Lower Insulin While Keeping A1C Stable

Start gently. If joint pain limits exercise, begin with 12-hour fasting windows and build up. Walk 15 minutes after meals to improve glucose uptake without stressing joints. Track both A1C and fasting insulin every 8–12 weeks—don't rely on A1C alone.

Insurance hurdles and embarrassment about obesity often delay help, but these changes require no costly programs. Consistency beats perfection—many see blood pressure improve alongside insulin normalization.

Long-Term Success With The CFP Weight Loss Method

Our method emphasizes sustainable habits over trendy diets. By addressing root causes like hormonal shifts and insulin resistance, clients regain energy and confidence. If you've failed every diet before, this isn't another quick fix—it's education that empowers you. Monitor progress with a simple journal of energy, cravings, and weekly measurements. Most notice reduced belly fat and better diabetes management within months. Remember, high insulin with normal A1C is fixable when you target the right markers with the right approach.

💬 What the Community Says

The community shows mixed experiences with normal A1C but high insulin during intermittent fasting. Many in the 45-55 age group report frustration after months of 16/8 fasting only to see fasting insulin remain elevated at 12-20 μU/mL despite A1C in the 5.2-5.6 range. A common theme is surprise that "healthy" fasting windows can raise cortisol and stall progress, especially with perimenopausal symptoms or existing blood pressure concerns. Most practitioners find that shortening the fasting period to 12-14 hours and adding more protein helps lower insulin without derailing A1C. A vocal minority debates testing frequency, with some advocating quarterly labs while others rely on continuous glucose monitors for real-time patterns. Lived experiences often mention joint pain limiting activity and skepticism after repeated diet failures, yet many share gradual successes when combining milder fasting with stress management and fiber-rich meals. Overall sentiment leans toward cautious optimism with calls for individualized adjustments rather than one-size-fits-all protocols.
Cite this answer
Clark, R. (2026). Does anyone have a normal A1C, but high insulin while doing intermittent fasting. *CFP Weight Loss*. https://ask.cfpweightloss.com/ask/does-anyone-have-a-normal-a1c-but-high-insulin-while-doing-intermittent
Russell Clark, FNP-C, APRN, FNP-C, APRN
About the Author

Russell Clark, FNP-C, APRN, is the founder of CFP Weight Loss in Nashville and CFP Fit Now telehealth. Over 35 years in healthcare — Army Nurse Reserves, Level 1 trauma ER, hospitalist — he developed a 30-week protocol integrating real foods, detox, and low-dose tirzepatide cycling that has helped hundreds of patients lose 30–90 pounds. He and his wife Anne-Marie lost a combined 275 pounds using the same protocol.

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