How does anyone have a normal A1C, but high insulin on a low-carb diet?

Understanding the Disconnect Between A1C and Insulin Levels

Many people following a low-carb diet are surprised to see their A1C in the normal range—typically under 5.7%—while their fasting insulin remains elevated above 10 μU/mL. This pattern is common in my work with adults aged 45-54 who have struggled with hormonal changes, joint pain, and previous diet failures. A1C measures average blood glucose over 2-3 months, reflecting how well sugar is managed. However, it doesn't capture the amount of insulin your pancreas must secrete to keep those sugars in check.

On a low-carb diet, glucose drops, so A1C normalizes quickly. Yet if underlying insulin resistance persists, your body compensates by producing more insulin. This is especially true during perimenopause or menopause when estrogen declines, making fat storage around the midsection more likely and worsening blood pressure and diabetes management.

Why This Happens on Low-Carb Diets

Low-carb eating reduces carb-driven glucose spikes, which is why it's effective for many. But for those with long-term insulin resistance—often built from years of high-sugar diets—cells in muscle, liver, and fat tissue respond poorly to insulin signals. Your pancreas ramps up production, leading to high circulating insulin even as A1C looks perfect. Stress, inadequate sleep, and hidden carbs can exacerbate this. In my book, I emphasize that simply cutting carbs isn't always enough; we must address the full metabolic picture including cortisol and thyroid function.

Numbers matter: Aim for fasting insulin below 5 μU/mL for optimal health. Levels of 8-15 μU/mL with normal A1C signal early metabolic trouble that could progress to type 2 diabetes if ignored.

Actionable Steps to Lower Insulin Without Overhauling Your Life

Start with simple tweaks that fit middle-income budgets and busy schedules—no gym marathons or expensive programs required. First, prioritize protein at 1.2-1.6g per kg of body weight daily; it stabilizes blood sugar and reduces insulin demand. Pair this with non-starchy vegetables and healthy fats like avocado or olive oil.

Incorporate gentle movement: 20-minute daily walks ease joint pain and improve insulin sensitivity by 20-30% within weeks. Track both A1C and fasting insulin every 3 months through affordable lab options many insurance plans partially cover. Manage stress with 10-minute breathing exercises to lower cortisol, which directly fuels insulin resistance.

My CFP Weight Loss approach focuses on these sustainable habits. By combining moderate carb cycling—adding 20-50g of carbs from berries or sweet potatoes on active days—you prevent metabolic slowdown while keeping insulin in check. Many clients see insulin drop 30-50% in 90 days without feeling deprived.

Monitoring Progress and When to Seek Extra Support

Use a simple journal to log energy, hunger, and waist measurements alongside labs. If insulin stays high despite normal A1C, consider underlying issues like sleep apnea or medication side effects. Don't be embarrassed to discuss this with your doctor—early action prevents complications with diabetes and blood pressure. Remember, past diet failures don't define you; targeted, low-effort changes create lasting metabolic repair.