Progress report

Sorry your wife is struggling. However, it can take some time for all our insulin producing cells to finally give up. The date of our Type 1 diagnosis is when enough have died to mean our pancreas is unable to produce sufficient insulin but not the date when they all die. My insulin dose slowly increased for the first 8 years after my diagnosis - as nothing else changed, I assume this is how long it took for the last insulin producing cells to finally pass away.

I think you are suggesting that you have changed your bolus (short acting) insulin dose rather than the basal (long acting. This is contrary to the usual advice. The long acting is a background which manages the glucose which is constantly dripped from our liver 24x7. I think of this as the foundation. If this is not right, any bolus (short term insulin) is dealing with this unstable foundation. The usual advice is to get the basal right (and then adjust bolus).
The correct basal is the dose that keeps your blood sugar levels stable (ish) in the absence of any food, exercise and other insulin. If injecting this once a day, this is easy to check - are the levels stable overnight?
Once this is about right, then, we can build upon those foundations to get the insulin to carb ratios correct. TO confuse things even more, the ratio may be different for different times of the day. It is not uncommon to be more insulin resistant in the morning so many of us have a higher ratio for breakfast than the rest of the day.

Does your wife use a Libre? This is really helpful for stabilising insulin doses. But only if you understand the limitations of CGMs (e.g. if the 24 you mentioned was read on a Libre, I would not trust it as they are calibrated to be accurate between about 4 and 9mmol/l.)

Bear in mind that ratios and doses do not remain the same for ever. As I mentioned, they can change as more insulin producing cells die off but also can be affected by stress, illness, exercise, etc.

The other thing to consider (if you want to) is pre-bolus time - if you find your wife's levels spike after eating but are back within required range by the next meal, this may be because the food is being digested before the insulin is active.

Sorry, I have gone on a bit and probably confused you even more .. for which I apologise ... so I will stop now.

@grahamrb I think you misunderstood me on the accuracy of Libre. It is calibrated to be accurate between 4 and 9. Outside of this range, I pretty much ignore what Libre says and always check with a finger prick unless it is reporting low and I definitely feel hypo and need to treat immediately.
Typically (although not always), I have found Libre over reports on highs but not by a consistent amount or percentage.
I am not surprised you have not been told about the limitations of the Libre. Unfortunately, few people are. However, they are frequently mentioned on this forum. The key points I remember are
- always check highs and lows with finger pricks.
- some people find they can take a couple of days to “bed in”. I always insert my sensor 48 hours before activating to give my body time to familiarise itself with the foreign object in my arm. Otherwise, the first couple of days readings seem to be random.
- pressure applied to the sensor can cause compression lows. This can result in false low readings ar night if you lie on your arm.
- interstitial fluid readings are about 10 to 15 minutes behind blood sugar readings. Libre attempts to predict the difference by extrapolating the current trend. This is not a bad prediction of the trend continue. However , if the trend changes direction it can be wrong. For example, when treating a hypo, it can show a continuation of the low when you are actually recovering.
- the sensors are factory calibrated against a fictional “typical person”. Some of us find we are not like this “factory man” and need to calibrate the sensor. This is not possible with the official LibreLink app so I use xDrip+ instead. xDrip+ is great if you are technically minded and are aware going “off piste“ is not officially sanctioned. i recommend checking against finger pricks at least once a day when the readings are flattish and between 4 and 9 even if you are using LibreLink.

As I mentioned, these points (and possibly more) are frequently mentioned on the forum so I recommend using the search function (top right) and reading through the comments as I may have missed some things.

As for changing bolus before changing basal, I believe this is a mistake as you are making tweaks against an unstable foundation.

I can have readings on the Libre above 9 and still find them bang on accurate with a blood test. The only time there tends to be a differential is when changes are happening very rapidly. But this is to be expected.