That can happen. (been there, done that, among other things!)
First - are there any indications that your cat is in immediate trouble? (See my signature link below for Secondary Monitoring Tools)
- if dehydrated, smelling of ketones, or seeming ill, go to a vet.
Second - You can stall 30 minutes without feeding and try for a test again. If the test is above 200 mg/dL for new members, and as far as you know, the middle of the inter-shot interval has never gone below 50 mg/dL on a human meter (68 mg/dL on a pet meter), you're likely safe to shoot.
If you're not sure how low your cat goes between doses, skipping a shot so you can sleep may be OK if your cat has never had ketones (testing for those is important!) and is otherwise doing OK.
If your cat has ever had ketones, giving a token dose (ex half of normal), will tide you over to morning, when you can gear up to work more on testing. Check for dehydration, food and water consumption and elimination, and if you can pick up some KetoDiaStix, you can test fresh urine for the presence of ketones. Ask the pharmacist for them as they are often behind the counter.
You mention neuropathy on the spreadsheet. Glucose control plus methylcobalamin (methyl B-12 vitamin) will help resolve that if it is from the diabetes. Your vet may have checked the potassium levels on your cat; if not, potassium deficiency can cause difficulty standing and walking, too.
We've got an entire section here with folks using Lantus and they are really great at coaching you on how to use it most effectively. Pop over to the Lantus section and start reading the sticky posts at the top on how to use Lantus most effectively.
Lantus is a depot insulin so the dose overlaps a little bit each time. This build up stabilizes over 5-7 days starting out, and then for changes, stabilizes over 3-5 days, so you have to give a dose that much time before determining if it needs to be increased. Also, dose adjustments are based on the nadir, the lowest glucose post-shot. That often happens between +5 to +7 hours after the Lantus was given.
When you have a moment, could you add a few tidbits to your signature? It will help us give you feedback.
Editing your Signature
In the upper right corner of the screen, within the dark blue bar, you will see ID, Inbox, and Alerts
Click on your ID.
On the left, under Settings, Click on Signature.
This is where you will put information that helps us give you feedback. You are limited to 2 hard returns, so separate pieces by | or -.
This is where you paste the link for your spreadsheet, once it is set up.
Add any other text, such as your name | cat's name | date of Dx (diagnosis) | insulin | meter general location (city and state/province) any other pertinent issues like if there are any food issues, history of DKA, hepatic lipidosis, pancreatitis, allergies, IBD, etc.
Click the Save Changes button at the bottom.
Always click the Save Changes button at the bottom when you have changed anything.