A diabetic cat that is wobbling, drooling, or pressing its head into a wall is probably hypoglycemic, not high. Treat first and measure second. Rub honey or glucose syrup on the gums, set a timer for 15 minutes, and call the vet while you wait. Below 3 mmol/L (54 mg/dL) is the line where treatment starts, whether or not the cat looks sick.
Treat at 3 mmol/L (54 mg/dL), not at symptoms
Home glucose meters read cat blood accurately enough for this decision, though they tend to read a little low on the ear vein. A reading under 3 mmol/L (54 mg/dL) means act now. Between 3 and 4.5 mmol/L (54 and 81 mg/dL) with symptoms, treat and recheck. A cat that is fine at 3.5 mmol/L after insulin may drop further in the next hour, because insulin is still working, so a single normal number does not close the case.
Sugar on the gums, not in the bowl
A hypoglycemic cat will not reliably eat, and food takes 30 to 60 minutes to raise glucose. Sugar absorbed through the gum lining works in 5 to 10 minutes. Put a pea-sized amount of honey, golden syrup, or glucose gel on your finger and smear it between the lip and the gum, on the outside of the teeth. Do not squirt it into the back of the throat; a cat that is dull may inhale it. If the cat is still able to swallow, offer a small amount of its normal food afterward to keep the level up.
Recheck at 15 minutes
Set a phone timer the moment the sugar goes on. At 15 minutes, test again or judge by behavior: head up, walking straight, no drooling. If the number is still under 3 mmol/L or the cat is no better, repeat the sugar and call the clinic. Do not keep pouring sugar in every few minutes without measuring; a rebound to 20 mmol/L (360 mg/dL) means hours of thirst, urination, and a confused insulin plan.
Unconscious: nothing by mouth
A cat that cannot swallow will not be saved by syrup and can die of aspiration pneumonia if you try. If the cat is limp, unresponsive, or convulsing, keep the airway clear, do not put anything in the mouth, and drive. Keep the cat warm on the way; hypoglycemia and hypothermia travel together. If breathing stops, start CPR. A veterinary team will give glucose intravenously, which works in under 5 minutes, and that is the only reliable route in a collapsed cat.
Insulin overdose and skipped meals
Most cases at home come from one of four mistakes: drawing up the wrong insulin, using the wrong syringe scale, giving the shot and then finding the cat did not eat, or giving a second dose because the first was forgotten. U-40 and U-100 syringes are not interchangeable, and a U-100 syringe used with U-40 insulin delivers 2.5 times the intended dose. If a shot was given and the cat refused food, check glucose every 2 hours for the next 8 hours; the nadir of most cat insulins falls 4 to 8 hours after injection.
Testing at home takes practice and pays for itself. Warm the ear with a rice sock for 30 seconds, prick the vein at the outer edge of the pinna, and take the smallest drop you can; a cold ear reads falsely low and sends you chasing a number that is not real. Write down every reading with the time and the hours since the last injection, because a value without that context tells the vet almost nothing.
Glucose reading, signs, and action
| Glucose | What you see | What to do |
|---|---|---|
| Under 2 mmol/L (36 mg/dL) | Collapse, seizure, cold, unresponsive | Nothing by mouth, drive now, keep warm |
| 2 to 3 mmol/L (36 to 54 mg/dL) | Wobble, drool, head pressing, dilated pupils | Honey on the gums, recheck in 15 minutes, call |
| 3 to 4.5 mmol/L (54 to 81 mg/dL) | Quiet, shaky, hungry, restless | Small meal, recheck in 30 minutes, skip the shot if due |
| 4.5 to 8 mmol/L (81 to 144 mg/dL) | Normal behavior | No action, keep the usual schedule |
| Over 16 mmol/L (288 mg/dL) | Drinking, urinating, dull coat | Not an emergency today, call about the insulin plan |
After the sugar works
Do not give the next insulin dose on the usual schedule without a vet's instruction. A cat that needed sugar has had an overdose or a missed meal, and repeating the dose can push it straight back down. Feed small meals every 4 to 6 hours for the rest of the day and keep testing. Write down the time, the reading, the sugar given, and the insulin dose and type, because the vet will rebuild the plan from those four numbers. Cats in remission after weight loss can drop suddenly on the old dose, which is why diabetes in cats recommends a glucose curve rather than a single spot check. A cat that will not eat at all is a different problem and belongs in cat not eating, while a full convulsion needs seizure first aid.
Do this now
- Test or judge, and treat anything under 3 mmol/L (54 mg/dL) immediately.
- Smear a pea-sized amount of honey on the gum, outside the teeth.
- Set a 15-minute timer and repeat the test before giving more sugar.
- If the cat is limp or convulsing, nothing in the mouth, straight to the clinic.
- Write down time, reading, sugar, and insulin dose for the vet.
Frequently asked
Can I use table sugar instead of honey?
Yes. White sugar dissolved in a few drops of water, corn syrup, or glucose gel all work on the gum. Honey is convenient because it stays where you put it, but it is not magic. What matters is that the sugar touches the gum lining and that you recheck the glucose in 15 minutes.
Should I skip the insulin if the cat did not eat?
Call the vet before deciding, but the common instruction is to give half the usual dose or skip it when a meal is refused, since insulin without food drives glucose down. Never give the full dose to a cat that has not eaten, and test glucose 4 to 8 hours later when the insulin peaks.
Will one low reading mean the diabetes is cured?
No. A single low reading after insulin usually means the dose is too high, the shot went into muscle, or the cat ate less than usual. Diabetic remission does happen in cats that lose weight, but it is confirmed with a glucose curve over 12 to 24 hours, not with one meter reading at home.