Expert Q&A

Does anyone have a normal A1C, but high insulin on a low-carb or ketogenic diet

Understanding Normal A1C With Elevated Insulin

Many people in their mid-40s to mid-50s following a low-carb or ketogenic diet report a perplexing lab result: normal A1C (typically under 5.7%) yet fasting insulin above 10-15 μU/mL. This pattern often signals early insulin resistance despite stable average blood glucose. Your A1C reflects three-month glucose averages, but fasting insulin reveals how hard your pancreas works to maintain that control. On keto, reduced carb intake lowers glucose spikes, normalizing A1C quickly, yet lingering hormonal shifts from past high-carb diets or perimenopause can keep insulin elevated.

Why This Happens on Low-Carb and Keto Diets

Hormonal changes during your 40s and 50s amplify this disconnect. Declining estrogen increases visceral fat, prompting higher insulin output even on under 50g daily carbs. Stress, poor sleep, and joint pain limiting movement further elevate cortisol, which raises insulin. In my book, I explain the Insulin Sensitivity Reset Protocol that targets these root causes without complex meal plans. Many with type 2 diabetes or high blood pressure see initial A1C drops within 4-6 weeks on keto, but insulin may lag 3-6 months behind without specific tweaks like strategic protein timing (1.2-1.6g per kg ideal body weight) and 12-14 hour overnight fasts.

Actionable Steps to Lower Insulin While Keeping A1C Stable

Start by tracking both markers every 8-12 weeks. Add resistance exercises 2-3 times weekly using bodyweight or light bands—gentle on joints yet effective for improving sensitivity (aim for 20-30 minutes). Prioritize 7-9 hours sleep and 10-minute daily walks after meals to blunt postprandial insulin. Supplement wisely: 2000-4000 IU vitamin D, 400mg magnesium glycinate, and berberine (500mg twice daily with meals) can reduce fasting insulin 20-30% in studies of middle-aged adults. Avoid over-restricting calories, as this spikes cortisol. My approach in CFP Weight Loss emphasizes simple swaps—swap evening snacks for herbal tea and protein-rich breakfasts within a 10-hour eating window—to reverse this without gym schedules or expensive programs your insurance won't cover.

Long-Term Success and Monitoring

With consistent application, most see fasting insulin drop below 8 μU/mL within 4 months while A1C stays optimal. This reduces diabetes progression risk and eases joint pain through reduced inflammation. Don't be embarrassed to discuss these labs with your doctor—pairing them with my straightforward methodology empowers sustainable change. Focus on progress, not perfection, to overcome past diet failures and conflicting advice.

💬 What the Community Says

The community shows a mix of experiences with normal A1C paired with high fasting insulin on low-carb or ketogenic diets. Many in the 45-55 age group report this pattern after 3-6 months keto, often linking it to perimenopause, chronic stress, or previous high-sugar diets. Most practitioners find adding walking, magnesium, and monitoring both markers helpful, with insulin eventually trending down. A vocal minority debates whether slightly elevated insulin (10-12 range) on strict keto is truly concerning if A1C and fasting glucose look good. Those managing diabetes and blood pressure alongside weight loss often share frustration about insurance not covering advanced testing. Lived experiences highlight joint pain limiting exercise but note that gentle movement and simpler meal timing yield better results than rigid plans. Overall sentiment leans toward cautious optimism, with users encouraging consistent retesting rather than panic.
Clark, R. (2026). Does anyone have a normal A1C, but high insulin on a low-carb or ketogenic diet. *CFP Weight Loss*. https://blog.cfpweightloss.com/ask/does-anyone-have-a-normal-a1c-but-high-insulin-on-a-low-carb-or-ketogenic-diet
Russell Clark, 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.

Have a follow-up question?
More Questions 200 answered
Upped dosage + changing patch day — evidence-based answer for CFP patients What a 55 water fast did for me for those with hypothyroidism or Hashimoto's Is this normal? Feels like a waste and its effect on metabolism and insulin levels How it looks when you lose 170 lbs. but are still a fat man — what most people get wrong about this 📖 30-Week Tirzepatide Reset — Our signature protocol using a single 60 mg box of medication cycled over 30 weeks to achieve lasting metabolic transfor… E Patch to Injections how long did you leave your patch on and how it connects to gut health and inflammation Had Dr. Gundry spoken about the vaccine while doing intermittent fasting What is this new frozen hell on a low-carb or ketogenic diet When period stopped did you feel like the worst pmdd of all time daily or on a low-carb or ketogenic diet 📗 The 30-Week Tirzepatide Reset — Get Russell's complete protocol → Anyone have experience switching from compound injection to pill: what to track and how to measure progress Anyone stopped responding to Mounjaro and had better results with retatrutide: best practices and common mistakes to avoid 📖 Phase 2: Aggressive Loss — A 40-day window of focused fat loss supported by low-dose medication and a specific lectin-free, low-carb nutritional fr… Is it even worth it anymore: best practices and common mistakes to avoid Did anyone else feel like Trintellix completely blunted their GLP-1 (Mounjaro/Wegovy) effect while doing intermittent fasting Le mounjaro peut il se conserver au frigo — what do certified weight loss coaches recommend? Estradiol Cypionate- I’ve been underdosing- what dose are you at for those with hypothyroidism or Hashimoto's What a month of paleo has done for me: what to track and how to measure progress 📖 High-Dose Dependency — The pharmaceutical trap of staying on maximum medication doses indefinitely, which we avoid through our smart cycling me… Can we talk about the founder: how to talk to your doctor about this Anyone use an auto injector for the compounded med for those with hypothyroidism or Hashimoto's 📗 The 30-Week Tirzepatide Reset — Get Russell's complete protocol → What a 55 water fast did for me while doing intermittent fasting How I feel every time I go grocery shopping while doing intermittent fasting What about oxalates if you're on a GLP-1 like semaglutide or tirzepatide Anyone have experience switching from compound injection to pill — how a functional medicine approach differs 📖 Hormonal Chaos — The internal state of imbalance caused by modern grains and refined carbs that overrides willpower and forces the body t… Can’t stand avocados or guacamole. Help on a low-carb or ketogenic diet 2.5 mg no longer working. Move to 3.5 during the weight loss plateau phase What tissues show the biggest metabolic remodeling in z2: best practices and common mistakes to avoid 📖 Non-Scale Victories (NSV) — Improvements in energy, sleep, and disease reversal that matter just as much as the numbers on the scale during your tra… How do you know you are in meno if you take continuous bc while doing intermittent fasting What about oxalates — how a functional medicine approach differs 📗 The 30-Week Tirzepatide Reset — Get Russell's complete protocol → Getting the run around or I just do not have PCOS ? POLL At what strength did Semaglutide become effective for you on a low-carb or ketogenic diet 📖 Leptin Sensitivity — Restoring your brain's ability to hear the 'I am full' signal, which is often muted by high-sugar diets and systemic inf… Any women here that never had a flat stomach in their lives during the weight loss plateau phase Cheat / treat days or meals: best practices and common mistakes to avoid Is tomato paste lectin free — what most people get wrong about this How To Speed Up Your Metabolism After 40 during the weight loss plateau phase So if you're spacing out your shots - what are y'all doing with extra injectors — what most people get wrong about this Sometimes after I take my Mounjaro shot I see this at the spot I gave the shot. Anyone know why: how to talk to your doctor about this E Patch to Injections how long did you leave your patch on — how a functional medicine approach differs 📖 Strategic Fat Loading — A critical 48-hour phase at the start of the reset where we prime the body with healthy fats to trigger the transition f… How I found out I had uterine cancer, what I wish I had known, and what everyone with PCOS should know about their period and the role of cortisol and stress hormones 📗 The 30-Week Tirzepatide Reset — Get Russell's complete protocol → Started at 270 pounds at the beginning of last year, at the end I was 179 pounds! How do I look for those with hypothyroidism or Hashimoto's Anyone have recipes or grocery lists and how it connects to gut health and inflammation Anyone use an auto injector for the compounded med: what to track and how to measure progress Best recipe book and how it connects to gut health and inflammation E Patch to Injections how long did you leave your patch on: what to track and how to measure progress How much are people paying for Estring: how to talk to your doctor about this 📖 Insulin Resistance — A condition where your cells stop responding to insulin, locking fat in storage; our protocol is designed to unlock thes… Same Workout Until it becomes Zone 2 — what does the research actually say? Had my annual physical today: what to track and how to measure progress Was so tempted to hit the drive thru today. Went to the store instead for those with hypothyroidism or Hashimoto's 📗 The 30-Week Tirzepatide Reset — Get Russell's complete protocol → Is it just me or is Hashimoto’s greatly underrepresented when you have PCOS or hormonal imbalances How long did you carry a pad post-menopause and how it connects to gut health and inflammation 📖 Rebound Weight Gain — The common 'yo-yo' effect caused by high-dose, continuous GLP-1 use; we prevent this through strategic cycling and metab… How are we getting enough protein? Tips please on a low-carb or ketogenic diet Has anyone been diagnosed with Hashimotos after going through emotional distress or chronic stress in general: best practices and common mistakes to avoid So if you're spacing out your shots - what are y'all doing with extra injectors: what to track and how to measure progress