Hello gaffer,
(This is a copy-and-paste of a reply I recently made on another thread. Hopefully it's helpful for you).
I don't know if this will apply to your situation, but it might be useful for you or others. It comes directly from personal experience.
I have used Lantus for around 10 years. Over the last 1 year I experienced a lot of overnight low blood-sugars. I did not realise the source of the problem for a long while (although with hindsight it seems clear).
Eventually I traced it to the fact that a large amount of my Lantus dose before bed (18 Units, split into 2 injections) was acting immediately, rather than evenly over 24 hours.
Lantus Insulin is slightly acidic; when the acidic solution hits healthy fatty tissue it forms tiny crystals. These crystals then dissolve at a uniform rate, giving a steady release of the Insulin over approximately 20 - 24 hours. The injection site is really important for Lantus. If you hit a non-fatty area (blood vessel, or muscle, or
possibly an area damaged by previous injections) then these crystals do not form correctly. This can mean large amounts of the Insulin active immediately and acting more like a Rapid Insulin.
I started to take more care with my Lantus injections, and for me the overnight lows stopped immediately. I now scrupulously avoid 1 area of belly tissue that had been damaged by Lantus injections with larger disposable needles over many previous years. And I now make sure to rotate my Lantus injection sites, ensuring to take a good pinch of healthy tissue. Basic stuff that I should have been doing anyway, I guess.
After this small change, the overnight lows stopped immediately and I was able to reduce my Lantus dose from 18 to 14, without changing anything else in my routine.
http://www.lantus.com/starting/how-to-use/choosing-site.aspx
The information available for Lantus does give all the right advice about how to inject. But it does not give any information regarding WHY it is important to get it right. How the Insulin is designed to work is not explained, and I think this is very unhelpful. Obviously there are serious effects if it acts more like a Rapid Insulin.
Regards,
Antony