Big BG drop every night .. any ideas please?

Hello,

I'm new to this forum but have enjoyed reading it with interest over the past few months, and already learnt a few new things, even though I'm an 'experienced' diabetic.

I've been a T1 for 43 years and now a retired young 70 year old! I have always taken my diabetes seriously and as a consequence have been well controlled over all these years and have never had any complications. But my biggest problem, which started a few years ago, is the really large drop in BG that I experience over night ... every night

My overnight BG drop is really large, about 8 - 10 mmol/l, so I have to ensure pre-bed reading of 12-14 mmol/l or else I'll be really low (<3) on waking. The attached screenshot is taken from my detailed spreadsheet where I monitor BG, carbs and insulin/carb ratios and any relevant data. It shows the BG Night Drop, and BG pre bed and on waking, all averaged over last 3 days to smooth out the trend. It covers the last approx 6 months since Feb.

I take Lantus 12u am and Humalog before each meal, calculated using my insulin/carb ratios, of about 50u in total. Usually I have Humalog before breakfast and evening meal, since lunch is just a single sandwich or fruit and doesn't require any insulin. Lantus is about 20% of total insulin intake. My carb intake is typically 140g.

Typical HbA1c is 7.5% which is higher than ideal but my consultant believes this is due to the higher BG prior to bedtime in order to compensate for the large BG overnight drop.

In conjunction with my diabetic consultant, I have tried various changes and tests to see if we can overcome this problem, but nothing seems to work ...

1) Since I was not using Lantus several years ago, we introduced Lantus ... made no difference.
2) Tried changing Lantus level ... made no difference, and current level of 20% of total seems right based on BG 2hr after meals.
2) Tried changing fast acting insulin, from Humalog to Apidra, ... made no difference.
(Now back on Humalog since Apidra production problem in late 2011).
3) A variety of different blood tests plus MRI scan of pancreas to check for any abnormalities .. all OK.

Control of BG during the day is typically fine, but very infrequently (every 4 to 6 weeks) I can get a totally unexplained large BG drop during the day or late evening and I have to eat 40-80g carbs to compensate even though no extra exercise or insulin taken. That level of carbs will raise my BG by 6-8 mmol/l. My insulin overnight appears to last a VERY long time, since I inject at 7pm, pre-bedtime BG measure at 12 midnight, and then again on waking at 7am, and sometimes have to eat even more carbs before breakfast at 9am.

I would welcome any suggestions that you knowledgeable posters have to offer which might help me overcome this issue ...... many thanks ....Jon

Hello CarbsRok,

Many thanks for your detailed reply and questions/suggestions .. really appreciated and it has made me think long and hard about what I need to 'trial and error' again!. Here are my replies against each of the points you raised....

Q1) If you are on a total of 12 units of basal (lantus) and bolus 40 units over 2 meals then thats one hell of a lot of insulin.
A1:- I was incorrect before about total daily carbs. When I became a T1 40+yrs ago I was told to have 40g each for 3 main meals plus 10g biscuit mid-am and mid-pm, and I've stuck roughly to that .. but have reduced carbs over past few years to prevent weight gain. But I have always adjusted my bolus depending on carb intake .. well before DAPHNE concept was introduced
- I've now rechecked my daily carbs and it is more like 100-120g (ave 110g). Bolus 40u over two main meals is based on ratio of 2.0 for breakfast and 2.5 eve meal
- DAFNE guidelines say .."T1s need a total of 0.5 - 0.8 units per kg of body weight each day. My weight is 11st 4lb (72Kg with BMI of 24) so this equates to (72Kg x 0.5u = 36u at low end) and (72Kg x 0.8u = 58u at high end). I think I'm at the 'high end' need level (58u in total) and DAFNE says .."50% should be basal and 50% bolus". Note: I know four other T1s and they are all on a basal of 40 - 55%.
- BUT my basal (Lantus) is only 20% (12u) which is possibly why my bolus needs to be so high (40u). I tried back in Feb with bolus of 26u and basal of 52u for one week (total: 78u with basal at 50%), but had a bad hypo one early morning .. so reduced the bolus back to 12u. But my ave BG during that week was better than normal. In hindsight I think that was wrong and will now start increasing to 50% and monitor very closely whilst reducing the bolus.

Q2) Also the fact you do not bolus for lunch points to major problems somewhere along the line. The idea of a basal insulin is just that a basal it does not cover for meals.
A2:- I only have 10 -15g carbs for lunch, to help maintain my weight, so it is not a normal meal of ~ 40g carbs. But the breakfast basal does seem to last through to lunchtime which I agree is strange
- I am now going to start doing a low Basal lunch injection to see if that improves my overall control

Q3) Have you done any basal testing? This involves skipping meals and blood testing every hour.
A3:- the only basal check I've done is BG at 2hr after meals, which looks OK at <9
- but I will try the every hour test you suggest

Q4) Once you have done some basal testing then perhaps work on your carb ratio as that's a bit for 140 carbs.
A4:-My consultant has told me many times, this is what my body requires to maintain good BG levels .. the insulin requirement is very personal and everyone is different. But see my answer to Q1 above for the details

Q5) Has it ever been discussed to change the time of your lantus insulin or even splitting it?
A5:- that is one of the things that I thought I might try if all else fails
- also perhaps switch from Lantus to Levemir to see if that makes any difference

Q6) Other things to also think about are absorption. Has anyone checked your injection sites.
A6:- good point, since I think the big night BG drop must be related to the insulin being more slowly absorbed than it should, hence it seems to still be working well after the 5hr limit for basal.
- I rotate the sites between different areas of my thighs. I used to use areas over my stomach but got quite severe loss of fat tissue (lipoatrophy) so now use my thighs.
- I will get my injection sites checked at next appt and also try other injection sites not used before.

Q7) Have you tried a different length of needle?
A7:- No and I have been using 5mm needles for many, many years. But my problem is only at night so not sure why this is relevant

Q8) If none of these things help perhaps think about asking for an insulin pump.
A8:- I don't see how an insulin pump would address the problem I am experiencing,
- Also the two basic NICE guidelines for needing a pump are not being met in my case:-
1) attempts to achieve target HbA1c levels with multiple daily injections result in the person experiencing disabling hypoglycaemia (repeated and unpredictable occurrence of hypo that results in persistent anxiety about recurrence and is associated with a significant adverse effect on quality of life)
2) HbA1c levels have remained high (that is, at 8.5% or above) on MDI therapy

Conclusion:Thanks to your excellent multiple questions I have now decided to re-appraise all aspects of my insulin & carbs regime, starting with Lantus increase to about 50%.[/b] I'll let you know how it goes .... many thanks

Y

Hi CarbsRok,

Just now completed my first fasting test to check hourly BG with a Basal of 16u (been on 12u for months but increased to 16u two days ago). Started on waking at 06:15am, no basal, no carbs and done tests every hour for 8 hours and the results are shown below.

You can see no big change for first 4 hours (06:15 to 10:15), but then a large increase (2.6) in next hour, then drop of 0.9 in next hour, followed by steady increase up to 10.1 by 14:15. At 10:45 I had a coffee with milk (2g carbs) which may have had a minor affect on 11:15 result where it increased by 2.6 in last hour. The last 2 hours show an increase of 1.4 and 0.9 per hr. So I stopped at 14:15 with BG of 10.1 and have taken 6u basal, but no carbs, which should bring BG back to ~5 in a few hours. I will continue hourly tests to see how quick it reduces.

Do you have any comments on these results?
What do you suggest I change basal dose by for tomorrow .. I was think ~18-20?

Time BG (Lantus =16u)
06:15 5.1
07:15 4.9
08:15 5.1
09:15 5.3
10:15 6.1
11:15 8.7
12:15 7.8
13:15 9.2
14:15 10.1

Regards Jonty