What is a normal glucose level for dogs?

Normal blood glucose in dogs is 70–120 mg/dL on a fasting blood sample. Non-fasting values can run slightly higher (up to 140 mg/dL) after a meal. Values consistently above 200 mg/dL suggest diabetes mellitus or another cause of hyperglycemia that needs investigation.

What causes high glucose in dogs?

The most common causes of high blood glucose (hyperglycemia) in dogs are: diabetes mellitus (most common in middle-aged to older intact females), Cushing's disease (hyperadrenocorticism), pancreatitis, corticosteroid medications (prednisone, dexamethasone), post-meal elevation, and less commonly stress (though dogs are much less prone to stress hyperglycemia than cats).

What causes low glucose in dogs?

Low blood glucose (hypoglycemia) in dogs can be caused by: insulinoma (insulin-secreting pancreatic tumor), Addison's disease (adrenal insufficiency), liver failure, sepsis, toy breed puppies (inadequate glycogen stores), insulin overdose in known diabetics, and prolonged starvation. Hypoglycemia is less common than high glucose but can be life-threatening — values below 40 mg/dL require emergency care.

Does high glucose always mean my dog has diabetes?

No. High glucose on a blood panel has several possible causes. Your vet will look at the clinical picture: Is the glucose just mildly elevated (121–200 mg/dL) or markedly high (above 300 mg/dL)? Is there glucose in the urine (glucosuria)? Are there classic diabetes symptoms — increased thirst, urination, appetite, and weight loss? A single high glucose needs context before a diagnosis is made.

What is glucosuria and why does it matter for dogs?

Glucosuria means glucose in the urine. Normally, kidneys filter glucose and reabsorb it all before it reaches urine. When blood glucose exceeds the 'renal threshold' — approximately 180–200 mg/dL in dogs — kidneys can no longer reabsorb all of it and glucose spills into urine. Finding glucosuria alongside high blood glucose strongly supports a diagnosis of diabetes mellitus.

What is fructosamine and when does my dog need it?

Fructosamine reflects average blood glucose over the past 2–3 weeks (similar to HbA1c in humans). It is not affected by stress or a recent meal. Your vet may run fructosamine when blood glucose is borderline elevated and they need to know whether it has been persistently high (suggesting diabetes) or was just a one-time spike. Normal fructosamine in dogs is roughly 225–375 μmol/L.

What glucose level is an emergency in dogs?

Low glucose emergencies: values below 40 mg/dL can cause seizures and brain damage — rub corn syrup on gums and go to a vet immediately. High glucose emergencies: glucose above 500 mg/dL with vomiting, lethargy, or fruity-smelling breath may indicate diabetic ketoacidosis (DKA), which requires immediate hospitalization with IV fluids and insulin.

Can Cushing's disease cause high glucose in dogs?

Yes. Cushing's disease (hyperadrenocorticism) causes excess cortisol, which raises blood glucose by promoting gluconeogenesis (making new glucose from protein) and causing insulin resistance. Many dogs with Cushing's have borderline to moderately elevated glucose (140–250 mg/dL) without meeting the threshold for diabetes. Some Cushing's dogs do develop diabetes as a complication.

Glucose in Dogs: Normal Range, High & Low Blood Sugar Explained

Dog Glucose Quick Facts

Normal range

70–120 mg/dL

(fasting)

High glucose

Diabetes, Cushing's,
pancreatitis, steroids

Low glucose

Insulinoma,
Addison's, liver disease

Seeing elevated glucose on your dog's bloodwork?

Upload the full panel — glucose makes most sense alongside BUN, creatinine, liver enzymes, and cortisol markers.

Analyze My Dog's Bloodwork

Your dog's blood panel shows a glucose value — but what does it mean? High glucose has several causes beyond diabetes, and low glucose is a separate emergency. This guide covers what the number means, how your vet interprets it in context, and what tests usually follow.

What Is Glucose on a Blood Panel?

Glucose is the primary fuel source for every cell in the body. The bloodwork value reflects how much glucose is circulating in the bloodstream at the time of the blood draw. It is a snapshot — not a 2–3 week average (that would be fructosamine, which your vet may also run).

Blood glucose is tightly regulated by two hormones: insulin (lowers glucose by letting cells absorb it) and glucagon (raises glucose by releasing stored glycogen from the liver). When this system breaks down — due to insufficient insulin, insulin resistance, or a glucose-producing tumor — blood glucose goes out of range.

High Glucose (Hyperglycemia) — Severity Chart

70–120 mg/dL

Normal

Meaning: Normal glucose regulation

Action: Routine wellness monitoring

121–199 mg/dL

Mildly Elevated

Meaning: Post-meal, early Cushing's, mild stress, steroids

Action: Recheck fasting; consider fructosamine

200–399 mg/dL

Elevated

Meaning: Diabetes likely; also pancreatitis, Cushing's

Action: Urinalysis for glucosuria, fructosamine, full panel

400–599 mg/dL

Severely Elevated

Meaning: Uncontrolled diabetes; check for ketones

Action: Urine ketones, start or adjust insulin urgently

600+ mg/dL

Critical

Meaning: DKA risk — life-threatening emergency

Action: Emergency hospitalization, IV fluids, insulin

Glucose Level	Severity	What It Suggests	Typical Next Step
70–120 mg/dL	Normal	Normal glucose regulation	Routine monitoring
121–199 mg/dL	Mildly Elevated	Post-meal, Cushing's, mild stress, steroids	Recheck fasting; fructosamine
200–399 mg/dL	Elevated	Diabetes likely; pancreatitis, Cushing's	Urinalysis, fructosamine, full panel
400–599 mg/dL	Severely Elevated	Uncontrolled diabetes; check for ketones	Urine ketones, urgent insulin adjustment
600+ mg/dL	Critical	DKA risk — life-threatening	Emergency hospitalization

Note: Glucose must always be interpreted alongside clinical signs and urinalysis. A single elevated value on a non-fasting sample does not diagnose diabetes.

Common Causes of High Glucose in Dogs

Diabetes mellitus — The most common cause of persistently elevated glucose in dogs. Cells cannot absorb glucose due to insufficient insulin (Type 1-like) or insulin resistance. Classic signs: increased thirst, urination, appetite, and weight loss. Glucose typically 300–600+ mg/dL with glucose in urine. See our full guide to diabetes in dogs →
Cushing's disease (hyperadrenocorticism) — Excess cortisol causes the liver to produce glucose and makes cells resistant to insulin. Glucose is usually mildly to moderately elevated (140–250 mg/dL). Other signs: pot-bellied appearance, hair loss, excessive drinking and urinating, skin changes. See our guide to Cushing's in dogs →
Corticosteroid medications — Prednisone, dexamethasone, and other steroids directly raise blood glucose through the same mechanism as cortisol. Even a single steroid injection can cause mildly elevated glucose for several days. Always tell your vet if your dog has had steroids recently.
Pancreatitis — Inflammation of the pancreas can damage insulin-producing beta cells, temporarily raising glucose. Pancreatitis-associated hyperglycemia may resolve once inflammation subsides, or may progress to permanent diabetes if enough beta cells are destroyed.
Post-meal elevation — Blood glucose normally rises after eating and peaks within 1–2 hours. A non-fasting blood draw can show values of 140–170 mg/dL in a healthy dog. This is why vets often ask for fasting bloodwork when glucose needs to be interpreted accurately.
Stress — Much less significant in dogs than in cats. Mild stress-related glucose elevation in dogs rarely exceeds 150–160 mg/dL and does not typically cause glucosuria.
Progesterone (intact females in diestrus) — Progesterone stimulates growth hormone release, which causes insulin resistance. Intact female dogs are significantly more prone to diabetes, and many cases can be put into remission simply by spaying during or just after diestrus.

Low Glucose (Hypoglycemia) — Severity Chart

55–69 mg/dL

Mildly Low

Signs: May be asymptomatic or mild lethargy

Action: Feed, recheck; investigate underlying cause

40–54 mg/dL

Moderately Low

Signs: Weakness, trembling, disorientation, staggering

Action: Rub corn syrup on gums; urgent vet visit

<40 mg/dL

Emergency

Signs: Seizures, collapse, unconsciousness

Action: Emergency IV dextrose — go immediately

Glucose Level	Severity	Typical Signs	Action
55–69 mg/dL	Mildly Low	May be asymptomatic or mild lethargy	Feed, recheck; investigate cause
40–54 mg/dL	Moderately Low	Weakness, trembling, disorientation	Corn syrup on gums; urgent vet visit
<40 mg/dL	Emergency	Seizures, collapse, unconsciousness	IV dextrose — go immediately

Common Causes of Low Glucose in Dogs

Insulinoma — A tumor of the pancreatic beta cells that secretes insulin continuously, regardless of blood glucose level. Causes episodic, sometimes severe hypoglycemia. Classic presentation: middle-aged to older dog with intermittent collapse or seizures. Requires imaging (ultrasound, CT) to locate the tumor.
Addison's disease (hypoadrenocorticism) — Insufficient cortisol impairs the liver's ability to release stored glucose (glycogenolysis). Often missed because symptoms are vague. The "great pretender" — hypoglycemia may be intermittent. Check electrolytes: low sodium and high potassium are the classic Addison's pattern.
Toy breed puppy hypoglycemia — Puppies under 3 months (especially toy and miniature breeds) have inadequate glycogen stores and can develop life-threatening hypoglycemia from missing even one meal, stress, or a GI upset. Feed small amounts frequently and watch for lethargy or weakness.
Insulin overdose — In diabetic dogs, too much insulin, a missed meal, or unusually high exercise can cause hypoglycemia. This is a known risk of insulin therapy and why glucose monitoring is essential. See the diabetes management section for what to do if a known diabetic dog goes low.
Liver failure — The liver is responsible for releasing glucose between meals (gluconeogenesis and glycogenolysis). Severe liver disease impairs this, causing fasting hypoglycemia. Usually occurs alongside other liver markers being abnormal (ALT, ALP, bilirubin, albumin).
Sepsis — Severe infection increases glucose consumption by bacteria and immune cells while impairing hepatic glucose production. Hypoglycemia with sepsis is a poor prognostic sign and requires intensive care.
Hunting dog hypoglycemia — Fit, high-energy working dogs can develop "hunting dog hypoglycemia" during prolonged intense exercise, depleting glycogen stores. Prevented by feeding a high-calorie meal before exercise and offering food breaks.

Not sure what your dog's glucose means in context?

Upload the full blood panel. VetLens reads glucose alongside BUN, creatinine, liver enzymes, and electrolytes to give you the complete picture — not just the flagged values.

Analyze My Dog's Results

The Tests Your Vet Will Run Next

When glucose is abnormal, it is rarely interpreted in isolation. Here are the follow-up tests typically ordered:

For High Glucose

→Urinalysis — check for glucosuria (glucose spilling into urine confirms the renal threshold has been exceeded, strongly supporting diabetes)
→Fructosamine — reflects 2–3 week average glucose, distinguishes true persistent hyperglycemia from a one-time spike
→ACTH stimulation / low-dose dexamethasone suppression — if Cushing's is suspected
→Lipase / pancreatic lipase (cPL) — if pancreatitis is suspected
→Urine ketones — if glucose is markedly elevated, to rule out DKA

For Low Glucose

→Insulin level measured simultaneously with glucose — if both insulin and glucose are collected at the same time, a high insulin with low glucose strongly suggests insulinoma
→Electrolytes — low Na, high K pattern points toward Addison's disease
→Liver function tests — bile acids, albumin, bilirubin if liver disease suspected
→Abdominal ultrasound — to look for insulinoma (pancreatic mass) or liver abnormalities
→ACTH stimulation — to rule out Addison's if electrolytes are suspicious

Glucose vs. Fructosamine: Which Tells You More?

Blood Glucose

• Snapshot of this exact moment
• Affected by recent meals, stress, exercise
• Fast and cheap — always included in a chemistry panel
• Best for: screening, monitoring known diabetics, diagnosing acute events
• Normal: 70–120 mg/dL (fasting)

Fructosamine

• Reflects average glucose over 2–3 weeks
• Not affected by meals, stress, or anxiety
• Add-on test — not always included in standard panels
• Best for: confirming diabetes vs. one-time spike, monitoring diabetic control
• Normal: 225–375 μmol/L

Note

When is fructosamine essential? When blood glucose is borderline (150–250 mg/dL) and your vet isn't sure whether this represents true diabetes or a transient elevation. A fructosamine within normal range rules out persistent hyperglycemia. An elevated fructosamine confirms the glucose has been high for weeks — diabetes is likely.

Signs of High Blood Sugar in Dogs

Mildly elevated glucose often causes no symptoms. When glucose becomes significantly elevated (above 200–250 mg/dL, especially if persistent), watch for:

• Increased thirst (polydipsia) — drinking much more water than usual
• Increased urination (polyuria) — urinating frequently, often in large amounts; accidents indoors
• Increased appetite (polyphagia) — ravenous hunger despite eating normally
• Weight loss — losing muscle and fat despite eating well (cells can't use glucose, so the body breaks down other tissues)
• Cloudy eyes — cataracts are a specific complication of diabetes in dogs; can develop within weeks
• Lethargy — overall reduced energy level

Warning

Signs of diabetic ketoacidosis (DKA) — seek emergency care: vomiting, severe lethargy, loss of appetite, fruity or sweet-smelling breath, rapid breathing, dehydration. DKA is life-threatening and requires hospitalization with IV fluids and insulin.

Signs of Low Blood Sugar in Dogs

• Weakness and wobbliness — legs may buckle, difficulty walking
• Trembling or muscle twitching
• Glassy or unfocused eyes
• Confusion or disorientation
• Seizures — at severely low levels
• Loss of consciousness — emergency

Emergency: What to Do If Your Dog Has Hypoglycemia Symptoms

1. Rub a small amount of corn syrup, honey, or maple syrup directly on the gums (not if unconscious — risk of aspiration)
2. Call your vet or emergency animal hospital immediately
3. If your dog is unconscious, go directly to an emergency vet — do not try to give anything by mouth
4. Keep your dog warm and calm during transport

If Your Dog Has Been Diagnosed With Diabetes

This article focuses on interpreting the glucose value on a blood panel. If your vet has confirmed diabetes mellitus, the next step is understanding how to manage it — including insulin selection, dosing, diet, home monitoring, and complications like cataracts and DKA.

Diabetes in Dogs: Symptoms, Diagnosis, Insulin & Management

Complete guide to canine diabetes — insulin types, diet, cataracts, home monitoring, and long-term management.

→

Consider Pet Insurance for Diabetes Management

Managing a diabetic dog requires ongoing care — insulin, syringes, glucose monitoring, regular bloodwork, and vet visits. Pet insurance can help cover these recurring costs. Plans start at $9/month.

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