This may be of some help, or maybe not...
One of the advantages of growing up with type 1 diabetes (there were a few actually) was learning early in life how to fuel properly and, how to recognise the symptoms of hypoglycaemia (low blood glucose) early and treat it appropriately. This was particularly useful when I was doing every daft sport and activity I could find while in my teens and into later life. People with type 1 diabetes who exercise regularly can also have an irritating habit of being able to keep going for longer than non-diabetics of comparable fitness, essentially because we've been training for it most of our lives.
When we talk about ‘bonking’ or ‘bonking out’ we’re generally referring to a state of hypoglycaemia, or ‘a hypo’ (low blood glucose), that occurs quite naturally during or after exercise, particularly when we’ve not fuelled correctly. Symptoms can include weakness, lethargy, mild confusion, cold sweats and nausea and vary in severity from feeling ‘mildly frazzled’ all the way to complete lapses in consciousness. Pretty serious!
Thankfully these symptoms can be treated quickly and effectively by taking 20-30g of fast acting carbohydrate in a relatively concentrated form. This will generally have you starting to feel better within 10 minutes, but it’s important to note that it can take significantly longer for your physical and mental state to recover to a point where you’re safe getting back on the bike; up to 45-60 minutes depending on how severe the hypo was and individual’s recovery rate.
Dextro Energy tablets, Lucozade Sport Gel and plain kendal mint cake (white) are particularly effective and relatively easy to carry and consume while exercising. The mint cake is particularly good as it can be eaten quickly without water due to the peppermint oil helping to stimulate saliva production. Sugary soft drinks can also be useful but the carbonation can make it difficult to get them down quickly. They can also do interesting things to some peoples' stomachs.
The key is for the carbohydrate to be easy to digest and highly concentrated. For that reason many sports gels are simply too weak in concentration to be effective hypo fixes. And to be fair, they’re not intended to be. Instead they’re formulated to provide a fuel source for regular ingestion ‘on the fly’ that is easily digested during extended and relatively intensive periods of exertion. More concentrated forms of carbohydrate (those suggested above) can cause digestive discomfort when taken during intense exercise if not taken with some fluid to dilute them slightly, but, they’re a far more effective ‘fix’ if you get caught out by crashing blood glucose.
And, if at all possible, AVOID CHOCOLATE and dairy! The dairy and vegetable fats in chocolate and chocolate syle confectionary can significantly slow digestion and absorption of the sugars you need to fix your hypo. Some jelly sweets can also be difficult to digest and so aren’t as effective as you might think.
It’s equally important to note that post-hypoglycaemia you’ll burn through whatever concentrated ‘fix’ you’ve taken quite quickly, so it’s key to get some longer lasting carbs on board relatively soon afterwards. Something like an energy bar with a more balanced sugars/non-sugars carb count is ideal (Clif Bars still work best for me) or a sandwich, some pasta, a cereal bar or even some crisps or chips will help in a pinch.
I’ve avoided talking about glycogen depletion and restoration because it’s quite a complex subject and actually not that helpful to the average cyclist. Suffice to say that if you really flake out completely then it can also take some time for your liver to restore glycogen levels, leaving you more susceptible to further bouts of hypoglycaemia in the hours (or even days) following the initial ‘bonk’.
I should qualify all of the above by saying that I am neither a medical professional, dietician, or a sports nutritionist. However, I am an active bloke in reasonable health, in my early 40s and have lived with type 1 diabetes for >30 years. Any products I’ve recommend are purely the result of years of trial and error in managing my own health in a wide range of quite challenging situations.
Hope this is helpful to someone.