Type 1 and fasting

It depends ...

If your on separate basal and bolus insulins and can adjust your doses then fasting is possible. You will need to adjust dosing (no bolus) and possibly reduced basal insulin to ensure you don't have a hypo.
Ketones are OK in normal range but some people do not tolerate elevated ketones well.
High ketone concentrations are dangerous.

You need to make sure you stay well hydrated.

I suggest you talk with your support team first ...

Yes, fasting is possible - no one apart from you can decide if it is "allowed" - if you are on a basal bolus insulin regime and are able to adjust your insulin doses.
However, I find Dawn Phenomenon makes it challenging to manage my morning BG without eating something. I may only need to eat something small but if I don't my body thinks it is starving and will continue to dump glucose and my BG will continue to rise until I eat something. This is beyond the early morning dump - it is a continuous BG rise until I eat. Therefore, fasting will be a challenge for me.
If you do fast, you must be willing to break your fast if you experience a hypo.

How long are you thinking of fasting, days or hours? It's definitely possible with medication adjustments as required. You'll have to treat any hypos and try again in a day or 2.

I have been doing a keto diet and have also managed a fast of 72 hours. When doing the keto diet, my blood sugar levels remain in target without the need to inject with meals. I do end up having to reduce my basal insulin. My diabetic consultant was happy for me to do the diet so long as my ketones were monitored and didn’t go higher than 2. I succeeded in losing 30kg in around 5 months.

My norm is to only have quite oat-milky decaff coffee most days until getting hungry, so meal approx 4-7pm, then snack before late bed.
Bolus altered as needed, basal 10 daily, 5 nightly.
When I wanted to lose weight, cut down on sweet stuff, crisps, potatoes, bread, and butter. More veg to fill up.
3.5 stones lost over 12months.
Medics have stopped arguing and accept it works for me.

I do 8pm - 12pm fasting most days with just coffee in the morning. I use an insulin pump and so I have absolutely no issues with Ketoacidosis or Dawn Phenomenon. If you do Basal/Bolus as the others say, you may have to adjust some things.

Does anyone take electrolytes when fasting?

Thinking of trying something more than intermittent fasting.

C.flem88 said:

Does anyone take electrolytes when fasting?

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Just want to preface this with - I'm type 2..

My routine is to essentially take a day off eating every fortnight or so, which results in a 36 hour fast. Beyond that I'll skip breakfast or lunch most days just to avoid a repeating schedule.

but I've found that (from long before being diagnosed) I would get cramps in my feet and calves during the night. This has improved enormously as I've gotten deeper into low-carb high-fat and fasting, but to get to the point - on those fasting days, while I feel great, I was starting to get crampy again, and it was getting worse, and clearly around the fasting.

Which makes sense, of course.. you don't stop sweating just because you're not eating.

so I now have about a gram of Himalayan salt a day. Himalayan, simply because it's got to have more stuff in it than chemical NaCl - sea salt should also, but the point being that even expensive crystalline Himalayan is incredibly cheap compared to anything advertising as "electrolyte" - when the vast majority of electrolytes is just salt, and stuff that you can easily get in food.

My sense is that salt is demonised along with fat, but what really happens is that when you cut carbs, there is simply less sugar in your body, so you "let go" more salt... and it's this that needs to be replenished. People sell "electrolyte" because it sounds more expensive, and more healthy, than "salt" - but it's mainly salt.

Anyway - short version - 20 twists of salt = about 1gm, so I do that into a small glass of carbonated water with a splash of raw apple cider vinegar and call it a tonic...

divadiane said:

I do 8pm - 12pm fasting most days with just coffee in the morning. I use an insulin pump and so I have absolutely no issues with Ketoacidosis or Dawn Phenomenon. If you do Basal/Bolus as the others say, you may have to adjust some things.

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Hi I started with a pump in May 2025, I’ve put on weight, and already overweight - LADA with insulin resistance. Just keep amending ratios so my insulin increases I’m thinking of fasting and wondered if you also exercise and if you just put your pump into the exercise range (mine is set at 8) Tia

I oft go 24 hours without eating.
I'm have MDI and with a libre and care sense dual monitor, to check keytones, and i find it a breeze in fact i did it on saturday but my motives are a bit different....
I suffer with bad guts so no food means less stomach problems and if i'm out and about its a needs must scenario.
I am always prepared to eat so theres no pressure.

I wish you well

Tony