Managing blood glucose levels on the diabetes rollercoaster: how low should you go?

Blog last reviewed on 28 July 2022. Things have moved on in terms of blood glucose targets and the Cochrane Review has not been updated, but Tom’s experiences of living with diabetes will be relatable for many, and we have kept the blog for his insights.

I’ve been talking to an expert on diabetes. He’s called Tom Hreben and he’s got 18 years experience under his belt. He didn’t choose it, though he is a health professional. He’s been living with it. Our expertise in Cochrane is in finding, putting together and interpreting the best available evidence, through preparing and publishing systematic reviews, to try and answer questions about health. This expertise needs to be joined up with that of people who can use it, including those who, like Tom, are managing health conditions such as diabetes. At best, a Cochrane review asks an important question about a treatment, finds great evidence that gives an answer, and patients, health professionals and policy makers find it really relevant and useful. If only this were always the case! The reality is generally much more messy, not least because, once health problems leave the pages of the textbook, they are messy and variable.

Good Morning by Jennifer Jacobs
Good Morning
by Jennifer Jacobs

I wondered how the Cochrane Review Intensive glucose control versus conventional glucose control for type 1 diabetes mellitus (published February 2014) squared with the reality of that for someone with type 1 diabetes mellitus (T1DM). The review, which compared intensive glucose control with conventional glucose control, aimed to help plug a knowledge gap, as there’s uncertainty about what levels people should aim for. The business of managing blood glucose levels is part of the daily work of managing this condition and it can be hard going. People with T1DM are given targets (that sounds like work too, doesn’t it?), suggesting what they should aim for with their glycaemic control, but it really isn’t at all clear what’s ideal, quite aside from what’s achievable. There are risks and benefits to weigh up. High levels can lead to long term problems affecting large blood vessels (macrovascular complications) such as heart attacks and stroke, or small blood vessels (microvascular complications) affecting the eyes, kidneys and nerves, for example. Aiming for low levels increases the risk of hypoglycaemic episodes, where low blood sugar levels cause problems such as loss of consciousness; it may be difficult to achieve and increase the fear of going ‘hypo’. Recent research has raised concerns that aiming for very strict glycaemic targets for people with type 2 diabetes could potentially cause more harm than good. We don’t know if this is so for people with T1DM too.

How does all this look to someone with diabetes?

I asked Tom. Here’s what he had to say:

“I feel obliged to first say that I don’t come here as an impartial patient who is simply offering their views on achieving good glycaemic control. I come to this as a healthcare professional. I’m a final year nursing student, due to qualify in the next six or so months and I get to see both sides of the fence. Thankfully however, I’ve not had an inpatient admission as a direct result of my diabetes in many, many years.

The best analogy to trying to achieve good glycaemic control that I can devise is one of a race. There are two runners, diabetes and you. This is a race in which you can only come equal to diabetes on your good days. On the days when you aren’t quite so on form, you lag behind; just how far you lag depends on quite how bad the day is. One catch, any other race has a finish, time when you can rest and recuperate. Diabetes doesn’t give you this chance, you run this race every day from the day you are diagnosed. For me, that was some time in August of 1996.

As much as I can understand the benefits of good glycaemic control which are patently obvious to see, I must add the caveats that have come from eighteen-odd years of dealing with this harsh taskmaster of an illness.

    • Bernard Bosanquet, credited with inventing the googly. Bernard Bosanquet, credited with inventing the googly. Watch out for the unexpected!

    It isn’t entirely a numbers game. To paraphrase Sir William Osler, the best diabetes teams will treat the person as opposed to the condition. You are not always going to be on a par with whatever your diabetes can throw at you, or for that matter whatever else your body can throw at you. There will be times when you simply cannot get a grip of the numbers and you are having a bad day. Accepting this is very important and isn’t an easy process. It’s all too easy for both patients and clinicians to become fixated upon numbers. Numbers aren’t necessarily an indication of quality of life.

  • Be prepared for being bowled a googly. You play by the rules, diabetes likes to change these rules. You might not see it coming but you’d best be able to adapt and fight back.
  • What else your body throws at you, in my case, some minor cardiac issues successfully treated. Diabetes can make these things a little more complicated but not necessarily insurmountable.
  • Yes, you can eat that. You really can. I might just crank the insulin up to eleven for that tub of Ben and Jerrys but if you try and tell me what I can and can’t eat because you know I’m diabetic, just you wait.
  • Mental health. Look after it and be aware of it.

Living with this is, as I have said a race in which you can only draw level with the lead runner. Keeping yourself in good nick is a balancing act. Knowing you won’t always be able to get it right is essential but getting obsessed over numbers isn’t going to do much either. Now, as a student nurse, I do want to advise people to aim for as good control as they possibly can achieve, I’ve seen the sorry consequences of it all too often when control hasn’t, for whatever reasons, been optimal for that patient. Tailoring care is so essential, as is continuing education. Times change and so must we.

To sum up then, I could wax lyrical for a long time here, living with diabetes and aiming for optimal glycaemic control can be a double-edged sword. The benefits are undoubtedly there but the cost of getting there is something that needs to be considered. I’ll be playing this game for a long time to come so, play up, play up and play the game.”

This is the messy reality of the ups and downs of life, common to all of us, with the additional challenges of managing a long term condition. Tom is absolutely right, of course, about tailoring care. Systematic reviews are fairly blunt instruments and deal in generalisations, but they are a starting point for patients and their clinicians when they are considering what might be worth trying.

Trapped by Jennifer Jacobs
Trapped by Jennifer Jacobs

So what can the research tell us?

The Cochrane review drew on evidence from 12 randomised controlled trials with over 2000 people. Here’s what they found:

  • Tight blood sugar control reduces the risk of developing microvascular diabetes complications. The evidence of benefit is mainly from studies in younger patients at early stages of the disease
  • Intensive glucose control can be associated with a higher risk of adverse events, such as severe hypoglycaemic episodes, ketoacidosis and weight gain. Results suggest that the risk of severe hypoglycaemia is particularly relevant for patients starting with lower levels (< 9.0%) of HbA1c (haemoglobin joined with glucose in the blood; this is tested to indicate blood glucose levels over a period of weeks) who aim for more intensive glucose targets
  • Risk of ketoacidosis was only increased in those studies that used insulin pumps in the intervention group, so ketoacidosis seems to be an adverse event of insulin pump therapy but not necessarily of intensive glucose control
  • The effects of tight blood sugar control seem to become weaker once complications have been manifested. Further research is needed on this
  • Evidence is lacking on the effects of tight blood sugar control in older patient populations, those who have lived with diabetes for a long time or those who received a late diagnosis, as well as on macrovascular complications
  • No firm evidence for specific blood glucose targets

How good was the evidence?

The reviewers judged it to be moderate to low quality evidence so further research may change the results. It’s quite old research too, with all but one of the trials done more than 15 years ago, so we have to consider to what extent these results still apply, given changes in treatment through the introduction of insulin analogues (altered, laboratory-made forms of insulin) and improved insulin pumps and a stronger focus on patient training and management. Also, the intervention and control groups differed not only in the glycaemic targets but also in the treatment regimes, frequency of self-monitoring and amount of contact with health professionals. It’s not possible to draw any conclusions about specific targets or how quickly patients should try to reach them.

The-Four-Seasons by Jennifer Jacobs
The Four Seasons
by Jennifer Jacobs

Where does that leave us?

This review suggests that there is no firm evidence on any specific treatment targets so I think we’re largely left in the dark. Treatment targets in current guidelines vary between an HbA1c of 6.5% and 7.5% and it is unclear how they were established. The evidence suggests that aiming for close to normal glucose levels in young people at relatively early stages of the disease should lower their risk of microvascular complications, but they will need training and support to manage the risk of hypoglycaemia. We know much less about the effects of intensive treatment for older people with diabetes or those who have already developed complications. The potential impact of tight blood glucose control on people’s quality of life, psychological factors such as fear of hypoglycaemia and a person’s ability to manage the regime all need to be taken into account along with the messy realities that Tom talks about. In the end, we can make rules based on evidence but, as Tom says, “diabetes likes to change them and you’d best be able to adapt and fight back.”

Living on the diabetes rollercoaster

I hope you have enjoyed seeing the work of New York artist Jennifer Jacobs in this blog, including the image above the title – Rollercoaster, in which Jen uses insulin bottles on glass. She says “Living with diabetes is like riding a rollercoaster. There are physical highs and lows (blood sugar and insulin), and emotional highs and lows.”  I’m always struck by how powerfully art can tell the lived experience of health and illness and in several of her fabulous pictures Jen uses diabetes supplies to tell her stories. Our thanks go to Jen for allowing us to reproduce her work here. For another view on this and more, from someone who also feels the pressure to keep their blood glucose low, do read this excellent blog from another health professional with T1DM, @anniecoops, along with her follow-up blog here.


Fullerton B, Jeitler K, Seitz M, Horvath K, Berghold A, Siebenhofer A. Intensive glucose control versus conventional glucose control for type 1 diabetes mellitus. Cochrane Database of Systematic Reviews 2014, Issue 2. Art. No.: CD009122. DOI: 10.1002/14651858.CD009122.pub2.

Managing blood glucose levels on the diabetes rollercoaster: how low should you go? by Sarah Chapman

is licensed under a Creative Commons Attribution-NoDerivatives 4.0 International

5 Comments on this post

  1. I want to thank you for a wonderful post. It’s great, the content is just perfect. Thank you for the important information you share with us.

    Dr. David Greene / Reply
  2. i like this article, it has a lot of info i need to know, thanks for sharing

    تمريض منزلي / Reply
  3. Why should diabetics have an average blood glucose higher than a normal person ? Is the extent of cardiovascular problems and other diseases a function of blood glucose and insulin levels ?

    Is a fear of hypos leading diabetics to consume too much carbohydrate, too much insulin and ultimately condemning them to “complications”. Why are carbohydrates a part of a diabetic’s diet in the first place ? Do clinical trials not show a benefit from reduced carbohydrate in the diet ?

    PhilT / Reply
    • To make it clear: Sarah’s blog was entirely about type 1 diabetes. For the much commoner condition of type 2 diabetes, we know surprisingly little to answer your very well directed questions. In type 1 diabetes, we are dealing with a spectacular and irreversible rise in sugar which is fatal within days or weeks without insulin treatment. It is caused by complete destruction of the insulin-producing cells in the pancreas, due to antibodies produced against them within the body. So it is not just an average difference in blood glucose: it is a catastrophic difference. As a result, people with this condition have to adjust their insulin levels every day and sometimes several times a day. How well they manage to keep control does indeed have a strong impact on outcomes such as heart disease, kidney disease and blindness, though this Cochrane review points out the uncertainties as well as the clear evidence.
      With type 2 diabetes the issues are mostly quite different, especially the relationship between glucose control and long-term outcomes. But there is indeed evidence in both types of diabetes that a low carbohydrate diet may be beneficial. This is the subject of another Cochrane Review from 2009:

      Richard Lehman, Cochrane Primary Care Advisor / (in reply to PhilT) Reply
  4. This is a brilliant post. I could write a book in response, but in essence, I totally agree that diabetes is NOT just a case of doing the sums and achieving great control. I’ve been T1 for 49 years. I have lots of experience and have watched over the decades as things have changed. What I’ve seen recently online causes me much fear for those newly diagnosed. Parents become totally obsessive about unrealistic targets, they think their kids will die overnight if they go even a bit low and the stress this causes them and THEIR T1 KIDS appals me. I fear greatly for their mental health – and their quality of life. There is much discussion about ‘beating’ diabetes – it can’t happen. You have to love it and live with it if you are to be happily controlled, and that involves being well educated in self management, feeling supported by clinicians when necessary and not hounded by them re targets, and having a community of other T1s to chat with where you can share and learn from your experiences and accept that we all have highs and lows and still live to tell the tale. I have few complications after 49yrs, despite periods of poor control in my teens. I have recently been using CGM which has shown me how difficult / impossible it is to keep blood sugars steady. Technology will never replace the miraculous workings of the human body when it’s operating efficiently. Insulin injections are a very blunt tool. But there are people who think they must achieve perfect control. I just wonder how relaxed and happy they are in their lives and whether they can have the freedom I think I’ve found now I’ve come to terms with knowing that my blood sugars will rock and roll at times. Although I’ve had numerous severe hypos in the past (pre CGM), and many minor ones now I’m more tightly controlled (post CGM), I have never been hospitalised for DKA in 49 yrs and I hope to keep it that way.

    Lis / Reply

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