Gluconeogenesis: The Hidden Reason Your Fasting Sugar Is High

Most people think high blood sugar comes only from eating carbs. But for millions of people—prediabetics, the insulin-resistant, and even those who appear healthy on the outside—blood sugar rises even when they haven’t eaten anything at all.

The reason is a quiet but powerful process inside your liver called gluconeogenesis, your body’s way of making new glucose from amino acids, lactate, and glycerol.

This article explains why your liver sometimes produces too much sugar, how it pushes your fasting glucose higher, and what signs indicate that this invisible process may already be happening in your body.

What Is Gluconeogenesis?

Gluconeogenesis is your liver’s built-in survival system. When you’re not eating—like during sleep or fasting—the liver keeps your blood sugar in a safe range by converting other materials into glucose.

It’s a normal, essential process.
But in modern life, dominated by chronic stress, sleep deprivation, overeating, and inactivity, this process becomes overactive.

When that happens, your blood sugar can rise:

overnight
in the early morning
between meals
even during fasting

And these elevated “baseline” sugars contribute heavily to your HbA1c, even if you rarely eat sweets.

Infographic showing the main causes of excessive liver gluconeogenesis, including insulin resistance, visceral fat, fatty liver, high cortisol, poor sleep, inflammation, low muscle mass, dawn phenomenon, and certain medications.” — Key drivers of abnormally high gluconeogenesis

Why the Liver Begins Making Too Much Sugar

1. Insulin Resistance (The #1 Cause)

In a healthy person, insulin signals the liver to stop producing glucose when blood glucose levels are normal.
But when you develop insulin resistance—long before diabetes—the liver becomes deaf to insulin’s signal.

So even when your blood sugar is high, the liver continues producing more.

This is why many people have:

fasting glucose of 100–110 mg/dL
normal post-meal sugars
rising HbA1c

The problem isn’t diet—it’s baseline liver output.

2. Visceral Fat Sends the Wrong Hormonal Signals

Fat stored around the organs (visceral fat) releases inflammatory molecules and free fatty acids that directly tell the liver to make more glucose.

This can occur even if your liver ultrasound is normal.
So a person can be:

not obese
but carrying extra abdominal fat
… and still have high gluconeogenesis.

3. Fatty Liver (NAFLD)

Non-Alcoholic Fatty Liver Disease, or Fatty liver, makes the liver extremely insulin-resistant, leading to elevated glucose production around the clock.

However, this is not the only cause.
Abnormal gluconeogenesis often precedes or occurs without fatty liver.

4. Chronic Stress and High Cortisol

Your body is wired to survive danger.
Cortisol, the stress hormone, signals the liver to release sugar for fast energy.

If you experience chronic stress or if you take steroids for medical conditions, your liver gets a constant message:

“Make more glucose—we’re in danger.”

Even low-grade, daily stress can raise fasting glucose.

5. Poor Sleep and Sleep Deprivation

One night of bad sleep increases insulin resistance the next day by 20–40%.
The liver compensates by increasing glucose output, sometimes causing morning blood sugar to jump 10–20 points.

This is a major driver of the dawn phenomenon—the early-morning rise in blood glucose that many people see even without eating.

The dawn phenomenon helps prepare the body for waking by boosting blood sugar levels and providing energy after an overnight fast.

6. Chronic Inflammation

Inflammation from infections, gum disease, autoimmune conditions, or obesity elevates cytokines like TNF-α and IL-6, which stimulate gluconeogenesis.

This is why people with chronic inflammatory states often have:

Higher fasting glucose
higher HbA1c
more insulin resistance

7. Low Muscle Mass (Sarcopenia)

Muscle is the body’s glucose sink.
When muscle mass is low, glucose disposal becomes inefficient.

The body compensates by raising baseline glucose production, pushing fasting numbers upward—especially in older adults or sedentary individuals.

Signs You May Have Excess Gluconeogenesis

You might not feel anything at first, but these clues are common:

Your fasting glucose is above 95–100 mg/dL
You experience a morning glucose spike (dawn phenomenon)
Your HbA1c is high despite “healthy eating.”
You have symptoms of insulin resistance (belly fat, high TG, low HDL)
You gain weight easily, especially around the waist
You feel “wired but tired” (chronically elevated cortisol)
You have difficulty lowering your glucose even with carb restriction

These are early clues that your liver is overproducing glucose.

Infographic listing the signs of excess liver gluconeogenesis, including high fasting glucose, dawn phenomenon, elevated HbA1c despite healthy eating, insulin resistance features, abdominal weight gain, wired-but-tired sensation, and difficulty lowering glucose even with carb restriction.” — Early clues that your liver is producing too much glucose

Does Excess Gluconeogenesis Happen Only With Fatty Liver?

No.
You can have dramatically elevated hepatic glucose output even with a perfectly normal ultrasound.

Other major contributors include:

visceral fat
inflammation
insulin resistance
poor sleep
stress hormones
medications
aging-related muscle loss

Fatty liver accelerates the problem, but is not required.

Medications That Increase Liver Glucose Output

“Infographic showing seven common medication classes that raise blood sugar: steroids, thiazide diuretics, beta-blockers, statins, atypical antipsychotics, oral contraceptives, and high-dose niacin.” — The drugs most likely to increase fasting glucose and HbA1c

Certain drugs can increase liver glucose production or worsen insulin resistance, raising fasting glucose and HbA1c even in people without fatty liver. These include:

1. Steroids (Glucocorticoids)

Prednisone, methylprednisolone, dexamethasone

Strongly increase gluconeogenesis
One of the most common medication causes of high blood sugar

2. Thiazide Diuretics

Hydrochlorothiazide (HCTZ), chlorthalidone

Cause insulin resistance
Frequently used for hypertension

3. Beta-Blockers (Especially Non-Selective)

Propranolol, nadolol

Decrease insulin secretion
May increase hepatic glucose output

(Cardio-selective ones like metoprolol may still have mild effects.)

4. Statins (Certain Types)

Atorvastatin, simvastatin

Can slightly raise fasting glucose
Pravastatin has the least effect

5. Atypical Antipsychotics

Olanzapine, quetiapine, risperidone

Strongly increase insulin resistance
Can significantly raise blood sugar

6. Oral Contraceptives (Estrogen-Containing)

Can raise glucose by reducing hepatic insulin sensitivity
More pronounced with higher estrogen formulations

7. Niacin (High-Dose Vitamin B3)

Impairs insulin sensitivity
Raises fasting glucose

How to Calm Down Excess Glucose Production

(Visual: switches turned “off” for cortisol, inflammation, visceral fat)

1. Build Muscle

Strength training increases insulin sensitivity and gives glucose a place to go.

2. Sleep Better and Longer

Sleep restores insulin signaling and reduces cortisol.

3. Reduce Visceral Fat

Even a small drop in waist size improves hepatic insulin response.

4. Manage Stress

Breathing, mindfulness during Mass, afternoon walks, and time in nature lower cortisol.

5. Reduce Inflammation

Treat gum disease, improve diet quality, increase omega-3s, and move daily.

6. Avoid Late-Night Eating

Eating late blunts insulin response and increases overnight glucose output.

7. Treat Fatty Liver (if present)

Weight loss, reduced fructose, resistance training, and intermittent fasting help restore liver function.

Why This Matters for Your HbA1c

Most people assume HbA1c only reflects what they eat, but at least half of the glucose contributing to HbA1c can come from the liver—especially in insulin-resistant individuals.

So when the liver keeps releasing sugar between meals, your HbA1c rises even if you avoid desserts and soda.

In Part 2, you will learn how:

fasting glucose
post-meal spikes
and gluconeogenesis

All combine to produce your final HbA1c score.

Don’t Get Sick!

Medically Reviewed by Dr. Jesse Santiano, MD
Dr. Santiano is a retired internist and emergency physician with extensive clinical experience in metabolic health, cardiovascular prevention, and lifestyle medicine. He reviews all medical content on this site to ensure accuracy, clarity, and safe application for readers. This article is for educational purposes and is not a substitute for personal medical care.

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References:

Sharabi K, Tavares CD, Rines AK, Puigserver P. Molecular pathophysiology of hepatic glucose production. Mol Aspects Med. 2015 Dec;46:21-33. doi: 10.1016/j.mam.2015.09.003. Epub 2015 Nov 5. PMID: 26549348; PMCID: PMC4674831. https://pmc.ncbi.nlm.nih.gov/articles/PMC4674831/
Shulman, Gerald I. “Ectopic Fat in Insulin Resistance, Dyslipidemia, and Cardiometabolic Disease.” New England Journal of Medicine, vol. 371, no. 23, 2014, pp. 2237–2238. https://www.nejm.org/doi/full/10.1056/NEJMc1412427.
Cusi, Kenneth. “Role of Insulin Resistance and Lipotoxicity in Non-Alcoholic Steatohepatitis.” Clinical Liver Disease, vol. 13, no. 4, 2009, pp. 545–563. https://pubmed.ncbi.nlm.nih.gov/19818304/
Roden M, Price TB, Perseghin G, Petersen KF, Rothman DL, Cline GW, Shulman GI. Mechanism of free fatty acid-induced insulin resistance in humans. J Clin Invest. 1996 Jun 15;97(12):2859-65. doi: 10.1172/JCI118742. PMID: 8675698; PMCID: PMC507380. https://pmc.ncbi.nlm.nih.gov/articles/PMC507380/
Rask-Madsen, Christian, and C. Ronald Kahn. “Tissue-Specific Insulin Signaling, Metabolic Syndrome, and Cardiovascular Disease.” Arteriosclerosis, Thrombosis, and Vascular Biology, vol. 32, no. 9, 2012, pp. 2052–59, https://pubmed.ncbi.nlm.nih.gov/22895666/
Goodman, Larry S., et al. Goodman & Gilman’s The Pharmacological Basis of Therapeutics. 13th ed., McGraw-Hill, 2018.

Disclaimer:
This article is for educational purposes and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult your physician before making health decisions based on the TyG Index or other biomarkers.

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Introduction

What Is Gluconeogenesis?

Why the Liver Begins Making Too Much Sugar

1. Insulin Resistance (The #1 Cause)

2. Visceral Fat Sends the Wrong Hormonal Signals

3. Fatty Liver (NAFLD)

4. Chronic Stress and High Cortisol

5. Poor Sleep and Sleep Deprivation

6. Chronic Inflammation

7. Low Muscle Mass (Sarcopenia)

Signs You May Have Excess Gluconeogenesis

Does Excess Gluconeogenesis Happen Only With Fatty Liver?

Medications That Increase Liver Glucose Output

1. Steroids (Glucocorticoids)

2. Thiazide Diuretics

3. Beta-Blockers (Especially Non-Selective)

4. Statins (Certain Types)

5. Atypical Antipsychotics

6. Oral Contraceptives (Estrogen-Containing)

7. Niacin (High-Dose Vitamin B3)

How to Calm Down Excess Glucose Production

1. Build Muscle

2. Sleep Better and Longer

3. Reduce Visceral Fat

4. Manage Stress

5. Reduce Inflammation

6. Avoid Late-Night Eating

7. Treat Fatty Liver (if present)

Why This Matters for Your HbA1c

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