Some of what you describe chimes with my own recent experience as a T2, currently awaiting test results to see if I am LADA (late-developing type 1 aka type 1.5). If you have any other auto-immune diseases (in my case thyroid disease) these would also be worth mentioning to your GP as risk factors for LADA/T1. Even if you don't have family history, it might be worth asking for a thyroid test as there is an association.
FBS in the 20s are unsustainably high and, although you say you don't have other symptoms, you are confident in your meter readings. This being the case, you should also ask for or provide blood or urine ketone readings. I had no idea what these where until very recently - in April, mine read at >4 which I have since understood as dangerously high. At the time I was beating myself up for not managing to reverse T2 and doing a lot of intermittent fasting; my GP thought fasting might have contributed to my high ketones (not unreasonably) and I could not be sure just how much my own stress levels and poor sleep were also contributing. I did, however, have a very dry mouth, thirst and needed to go to the loo a lot. The thing that did freak was that started to loose increasing amounts of weight after a point when I really no longer wanted to (eating loads, albeit low carb high fat and still harbouring a belief that I might do my own wholesome real food Newcastle diet). Insulin is a fat building hormone, and my latest working hypothesis is that I was losing weight not in a positive planned way, because of my low carb/intermittent fasting (strategies which had worked well earlier), but because I simply was no longer able to produce enough of my own insulin, so ended up burning fat and weeing out sugar (not a fab combo!)
We are all different and cannot give medical advice to each other, but I have found anecdotal information on this site a great help. Reading your posts, I think you have been more diligent on the diet front (although low carb, I have never wished to do keto), and I have been more active on the exercise front (walk/jog 6-8 miles most days, plus a lot of gardening).
I have cut and pasted a bit of my personal background, which may (or may not!) be of interest:
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Between the ages of 30-50, I was overweight, gradually moving up the ranks to full-blown obesity. When I turned 50 I set myself a goal of losing 4 stone over two years. I never really understood how carbs and calories were different but through trial and error I came up with my own DIY weight loss protocol: lots of walking and c1800 cals a day of which no more than a third from carbs, which I estimated at 150g a day. This worked very well for me and I found I was comfortably losing 2-3 pounds every month. When I was diagnosed with type 2 nine months into my regime, I had already lost 1.5 stone (c.10kg) and a tenth of my body weight. The Dr explained the parameters for diagnosis had recently changed, but that at HbA1c of 49, I was officially diabetic. Must admit my initial reaction was disbelief and extreme annoyance that things had changed, but it did spur me on to carry on with my diet and exercise routines.....now I know a lot more I suspect I had probably been diabetic for some time. Three months later my HbA1c had come down to 46 and I was congratulated on "reversing" my diabetes(!)
I lost three stone in a little over a year, and basked in the praise of the local practice nurse......I kept the weight off for a year, and then stressful work and family illness threw me off course, and weight started creeping back on. Nonetheless it was still an unpleasant shock to me when my GP suggested the time had come to start Metformin. It was then that I found this forum and started reading up, and realised that of course I hadn't reversed anything. I responded very well to Metformin (2 x standard 500mg - never had any problems with digestion after the first week or so) and discovered the joys of intermittent fasting, low carb baking and so much else! Over the course of seven years I have lost over five stone (34kg) and a third of my body weight but very, very slowly.
Things started to unravel a bit last summer and Metformin was increased to 1500mg. Then I had a step change in April, no matter what I tried I suddenly couldn't get my blood glucose lower than 15. Started on full whack Metformin (2000mg slow release) and 2mg Glimepiride, fully expecting great results....absolutely zero response, moved up to 4mg Glimeperide and still no improvement. Started panicking, GP told me to hang on in there and give it a chance, but ended up getting referred to the local hospital service and started insulin three weeks ago ago.
I can't tell you how much better I feel now, I don't think I realised how poorly I was until I started insulin. I had high ketones and probably did very well to avoid diabetic ketoacidosis (DKA). The new approach does take some getting your head round, though.
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I wish you the very best of luck in your diabetes journey. My own diabetes team is not exactly a dream team, but like my mid-table Championship side (OK Sheffield Wednesday!!!) they are still my team......I swerve on most of the dietary advice given, but have come to accept that when some blood sugar readings are alarmingly high or low (latter yet to be experienced in my case), despite best endeavours, then a medical approach is needed
Big hugs xx