If your cat’s blood sugar is dangerously low, rub a small amount of corn syrup or honey directly onto the gums. Do not pour liquid into the mouth, as it can reach the lungs. Normal feline blood glucose sits between 80 and 100 mg/dl, and a cat is considered hypoglycemic when levels drop below 65 mg/dl. Here’s what to do and what comes next.
Recognize the Signs First
Low blood sugar in cats shows up as weakness, wobbliness, disorientation, and trembling. A mildly hypoglycemic cat may seem “off,” acting dazed or lethargic and refusing food. As blood sugar drops further, you may see muscle twitching, loss of coordination, and eventually seizures or collapse. These signs can progress quickly, so acting fast matters.
Emergency Steps at Home
If your cat is alert enough to eat, offer food immediately. A high-protein wet food is ideal. If your cat won’t eat or seems too disoriented, move to a sugar source.
Keep Karo corn syrup or honey in your home if you have a diabetic cat. Rub a thin layer directly onto the gums using your finger. The sugar absorbs through the gum tissue and doesn’t need to be swallowed. The general guideline is roughly 1 tablespoon per 5 pounds of body weight, but in practice, a small amount rubbed on the gums is enough to start raising blood sugar while you prepare to get to a vet. Plain sugar dissolved in a small amount of water works in a pinch.
If your cat is unconscious, do not put anything in the mouth. This is a veterinary emergency. You can carefully lift the lip and rub a small amount of corn syrup on the outer gum surface, but your priority is getting to the nearest animal hospital.
What Causes Low Blood Sugar in Cats
The most common cause, by far, is an insulin overdose in a diabetic cat. This can happen from a dosing error, giving insulin when the cat hasn’t eaten, or when a previously stable cat’s insulin needs suddenly change due to illness. Cats are actually more likely than dogs to experience insulin overdoses. Vomiting or reduced food intake paired with a normal insulin dose is a frequent trigger.
Less common causes include severe infections (sepsis from conditions like a uterine infection or infected chest fluid), liver disease, and rarely, insulin-producing tumors of the pancreas called insulinomas. Very young kittens can also develop low blood sugar simply because their small bodies can’t store enough glucose. If your cat isn’t diabetic and develops hypoglycemia, something else is going on that needs a veterinary workup.
What Happens at the Vet
Once at the hospital, the veterinary team will give intravenous dextrose (a concentrated sugar solution) to bring blood glucose up quickly and reliably. Your cat will then receive IV fluids with added dextrose to keep levels stable over the following hours. Cats that arrive with severe neurological signs, like stupor or coma, or those that don’t improve within 12 hours of treatment, typically need intensive care and a longer hospital stay. Cats that respond quickly to initial treatment generally recover well.
The Somogyi Effect: When Sugar Spikes After a Low
One tricky complication of hypoglycemia in diabetic cats is called rebound hyperglycemia, or the Somogyi effect. When blood sugar drops too low, the body releases stress hormones that flood the bloodstream with stored glucose. The result is a dramatic spike, sometimes reaching 400 to 800 mg/dl, that can last 24 to 72 hours. During this rebound period, insulin injections may barely lower blood sugar at all.
This creates a dangerous cycle. If you see persistently high blood sugar readings after a suspected low, resist the urge to increase the insulin dose. That high reading may actually be your cat’s body overcorrecting from a low you didn’t even notice. Increasing insulin at that point would cause another crash. This is one of the main reasons regular blood glucose monitoring is so important.
Preventing Future Episodes
Home blood glucose monitoring is one of the best tools for catching lows before they become emergencies. The standard approach is to check your cat’s blood sugar before giving insulin and then every 2 hours for a 12-hour period to create what’s called a blood glucose curve. This curve shows how low your cat’s sugar dips (the nadir), when insulin peaks, and how long it lasts.
The goal for most diabetic cats on twice-daily insulin is to keep blood sugar between a low of around 80 to 100 mg/dl and a high of roughly 250 to 350 mg/dl throughout the day. If the lowest point on the curve drops below about 90 mg/dl (5 mmol/l), the insulin dose is typically decreased by 1 unit. If it stays above 160 mg/dl (9 mmol/l), the dose may go up by 1 unit. These adjustments should always be guided by your veterinarian based on the full curve, not a single reading.
A few practical habits reduce risk significantly. Always make sure your cat eats before giving insulin. If your cat vomits a meal or refuses food, skip the dose and call your vet. Keep a consistent feeding schedule, and store your corn syrup or honey somewhere easy to grab in an emergency. Check in with your vet at least monthly to review blood glucose data and adjust the plan as needed.
Feeding After a Hypoglycemic Episode
Once your cat is responsive and willing to eat, offer small amounts of food. A low-carbohydrate, high-protein wet food is the best option, as it provides steady energy without causing a rapid blood sugar spike followed by another drop. Avoid treats or foods high in simple carbohydrates. Keep portions small and frequent over the next several hours rather than offering one large meal, and hold off on the next insulin dose until you’ve spoken with your vet about how to safely resume the schedule.