More Diabetes Answers

Group Health Senior Caucus on March 20th

I am looking forward to speaking to anyone interested in diabetes at the Group Health Senior Caucus on Friday March 20th.  I am told that some of the written materials that were sent out have the wrong date on them and say March 2nd.  The correct date is March 20th.  I should be speaking between 10 a.m. and noon.  the location is at the Central Main Buidling (the old Group Health Hospital) at 201 16th Avenue East in Seatlle up on Capitol Hill.  We will be in the Doctors Lounge on the 6th floor.

I will be happy to answer any questions that you have about diabetes.

Why does the average blood glucose from my meter give me a different number than the eAG?

In a recent post I explained how it is possible to tell you what your average blood glucose level has been for the past 2-3 months by knowing your HbA1c.  Although this is meant to be helpful it can sometimes be confusing.  Let's say you test your blood glucose 3 or 4 times a day.  If you have a memory meter it will probably tell you what your average has been in the last 14 or 30 days.  Let's say that average is 183 mg/dL (or 10.1 mmol/L).  If you look at the table comparing HbA1C to the estimated average glucose (eAG) you would expect that when your HbA1c is tested it will be 8.0%.  but what if your HbA1c comes back at 9.8%, almost two whole percentage points higher than you meter average would have predicted.  What is going on?  The problem is probably not with your meter or with the accuracy of the lab test.  If your HbA1c is 9.8% this means that for the past 2-3 months your average blood glucose level really has been somewhere between 226-240 mg/dL (12.6-13.4 mmol/L).  The average that your meter gives you is simply the average of all the blood glucose tests that you did.  If you only test before meals or when you are feeling low, for example, and are not testing after meals or when you feel that your blood glucose is high then your "meter average" will be an underestimate of what your actual average is; it is not adding in the higher numbers to the average.  On the other hand if your "meter average" is higher than the eAG from your HbA1c test this suggests that there must be times during the day when your blood glucose is low when you are not testing.

So you can really make good use of this eAG number.  If it suggests that your blood glucose levels are higher than you thought from the tests you are doing every day then you should consider testing one or two hours after your main meals to see if it goes high at that time.  If the eAG is lower than you expected then it is likely that your blood glucose level is going low at times when you are unaware of it.  This can often happen during the night when you are asleep so it might be a good idea to test then to see if that is happening.

It is certainly a good idea to discuss your eAG with you doctor and health care team if the results don't make sense to you.

What is the Estimated Average Glucose (eAG)?

One of the most important numbers that you should track if you have diabetes is your HbA1c number (sometimes called glycosylated hemoglobin or hemoglobin A1c or simply A1c).  the HbA1c number tells you what percentage of the hemoglobin protein in your red blood cells has got glucose attached to it.  If the number is high this tells you that your average blood glucose level for the past two or three months has been high.  I explain this in more detail in Chapter 7 of The Diabetes Answer Book.  For people who don't have diabetes the HbA1c will be between four and six percent.  If your diabetes is really out of control more than 10 percent of your hemoglobin will have glucose stuck onto it.  For most people with diabetes the HbA1c is between 6-10% (and if you can safely keep it closer to 6% than to 10% that is great).

Because most people are more familiar with thinking of their blood glucose levels the American Diabetes Association is pushing for laboratories to not only give people their HbA1c result but to tell them what their average blood glucose level must have been for the past 2-3 months to get that HbA1c number.  The reason that this is possible is because of a very well-designed study that was published in the Journal Diabetes Care in August 2008.  Dr. Nathan and his colleagues worked with 507 subjects (268 had type 1 diabetes, 159 had type 2 diabetes, and 80 did not have diabetes at all) at 10 international research centers.  Over a six month period each subject checked their own blood glucose 7 or 8 times a day at least three days a week (before and90 minutes after each meal, before bedtime and once in the middle of the night).  In addition they wore a continuous glucose monitoring system (CGMS) on eight days during the six months.  So each subject had about 2,700 blood glucose tests done during the six month period as well as having their HbA1c checked several times during the same six months.  By taking an average of all these blood glucose tests and comparing them to the HbA1c taken during the same period the researchers found a very strong and straight relationship between the two.  They were able to construct a table which shows the average blood glucose level for each HbA1c.  Ihave shown this for a variety of HbA1c levels in the table below.  So the next time you get told what your HbA1c test result is you can look at this table and see what your average blood glucose level has been for the past 2-3 months.  The middle column is in "American" units of mg/dL and the right hand column give the estimated average glucose in International units of mmol/L.

HbA1c	eAG (mg/dL)	eAG (mmol/L)
6.0	126	7.0
6.5	140	7.8
7.0	154	8.6
7.5	169	9.4
8.0	183	10.1
8.5	197	10.9
9.0	212	11.8
9.5	226	12.6
10.0	240	13.4
10.5	255	14.1
11.0	269	14.9

 

Do the benefits of good blood glucose control ever wear off?

Keeping your blood glucose close to normal will definitely make you less likely to get eye damage or heart disease in the future.  But doing everything to keep your blood glucose close to normal is really hard work.  Watching what you eat, checking your blood glucose a lot, making adjustments in your food, exercise, pills or insulin... the constant grind of paying attention to every little detail can wear you out.  Some people can manage it for months or years on end, but others find that they can't keep it up all of the time.  They worry that if their blood glucose levels drift up that they will have lost all the benefit of those years when they kept it close to normal.  Some recent research studies give very encouraging results about this.

The biggest study looking at the effect of blood glucose control on long term complications for people with type 1 diabetes was the Diabetes Control and Complications Trial (DCCT).  After six and a half years of the study the people who kept their blood glucose closer to normal had a lot less eye damage, kidney damage and nerve damage than those whose blood glucose levels were higher.  At the end of the study the difference in blood glucose control between the two groups (those with "intensive management" and those with more regular treatment) was lost in a year or two.  In other words those who had been managed intensively to keep their blood glucose control close to normal "slacked off" a little while those in the less intensive group tightened up their efforts a bit.  So for the next several years all the people who had been in the DCCT had about the same level of control as each other.  The surprising thing was that the group who HAD kept their blood glucose levels closer to normal for the six and a half years of the study continued to have lower rates of eye damage, heart disease and other problems.  The benefits of their years of hard work continued even when they had "slacked off."

Just recently the same thing has been found for people with type 2 diabetes.  The largest study to look at the effects of blood glucose levels on diabetic complications for people with type 2 diabetes was the United Kingdom Prospective Diabetes Study (UKPDS).  That study showed that people who kept their blood glucose closer to normal had fewer problems with their eyes and blood vessels and heart.  It has been over ten years since the UKPDS finished.  Within a year the blood glucose levels for the people in that study had drifted closer together so that for the next eight to ten years they all had about the same level of blood glucose.  But once again, those who HAD kept their blood glucose closer to normal during the study continued to have healthier eyes and hearts than those who had had higher blood glucose levels during the study.

I think the follow up results from the DCCT and the UKPDS are very encouraging.  What they tell us is that if you can keep your blood glucose levels close to normal for many months or years that the benefit you get from this lasts for a very long time.  So if you drift for a while and can't keep things as close to normal as you used to don't beat up on yourself.  There are times when your life circumstances change and it is harder to do everything right.  Maybe you got divorced.  Maybe you lost a job.  Maybe you are looking after a family member who is ill and it takes up all of your time.  If your average blood glucose levels are not as good now as they used to be don't be discouraged.  Your body is still getting the benefit from all those years when you kept your blood glucose levels close to normal.  And if you can get back on track and bring your average back down again you will get even more benefit.

Do Continuous Glucose Monitoring Systems (CGMS) really improve your diabetes control?

I certainly hope so, but just like with so many things in life the difference between the hype and the reality is a bit sobering.  Although there had already been a few promising small trials with CGMS the first big randomized controlled trial in patients with type 1 diabetes was published on September 8th 2008 in the New England Journal of Medicine (a very prestigious and respected medical journal).  Let me describe the study and then try to explain what the results mean.

At 10 different medical centers 322 patients with diabetes were randomly assigned to use one of three CGMS devices (The DexCom Seven, the Minimed Paradigm, or the Freestyle Navigator) or to continue with traditional finger stick blood glucose testing only. They were divided into three age groups (8-14yo, 15-24yo and 25 or older, the average age in this last group was 44yo).  The average HbA1c level in these patients before the study started was between 7.6-8.0%.  They were already doing an average of six finger stick blood glucose tests a day.  They were mostly well-educated (three quarters of the patients or the parents of the kids had college degrees).  They were all doing intensive insulin treatment (80% were using an insulin pump and the other 20% were taking multiple insulin shots a day of both long-acting and fast-acting insulins).  In other words this was a highly motivated group of people who would be expected to do really well.

They were seen seven times in person during a six month period of the study.  In addition they had seven scheduled phone visits with the research team in between their in-person visits.  During these visits they were given advice and suggestions for how to interpret their glucose results and encouragement to change their insulin treatment and food and exercise to help keep their blood glucose as close to normal as they could while trying to avoid going too low (hypoglycemia).

Given everything that I have said the results were quite disappointing.  At the end of six months the only group who showed a significant improvement in their average blood glucose control were the older adults who got a drop of HbA1c of about half a percentage point (0.5%).  The group aged 8-14yo and 15-24yo showed no improvement in HbA1c compared to the people who continued to use traditional finger stick tests only.  Even more surprising to me was that none of the groups using CGMS had significantly fewer low blood glucose episodes (hypoglycemia).

What can we make of this?  It tells us that if you are highly motivated and are using frequent traditional finger stick blood glucose testing then you can achieve really good blood glucose control and that adding a continuous glucose monitoring system may not improve things much further.  Now I am quite sure that some of the patients in the study would say that the CGMS made them feel more secure because they knew what their blood glucose was all the time.  There probably were some patients who felt they could push their HbA1c levels closer to normal more safely by having the CGMS but clearly this was not seen in everyone.  The study was only six months long, too.  Almost any novel treatment will help improve HbA1c in a group of people with diabetes during the first six months, especially if they are being seen up to 14 times by an enthusiastic and supportive research team.  I worry that in a "real world" setting where people would get less close supervision and support and where the novelty of the CGMS might wear off after six months that the results might be even more disappointing.

Here are a few other things to think about.  None of the people in this study had their CGMS device automatically connected to their insulin pump.  This study was not testing an "artificial pancreas" set-up where the continuous glucose readings are automatically transmitted to the insulin pump which then automatically adjusts the insulin dose (I say more about that idea in The Diabetes Answer Book).  Studies like that will be done in the next few years and should give interesting results.  People who want CGMS because they think it will make their life "easier" may be disappointed, just as people who want an insulin pump so that they won't have to think about their diabetes so much are often disappointed.  Both of these technologies can be an amazing help to some people and with more studies we will learn more and more how to use them most effectively.

Truthfully I was expecting the results from this study to be much more impressive.  Clearly continuous glucose monitoring systems are not a "magic bullet" to make life with diabetes totally easy.  They may be a step in that direction, however, if we can figure out how best to use them.

How low is too low for blood glucose?

As I discuss in The Diabetes Answer Book there are debates between doctors and research scientists about what the best average blood glucose level (usually measured by a blood test called glycosylated hemoglobin or HbA1c) should be for people with diabetes.  Should the target be less than 8.0%, less than 7.0%, or what?  Should there be different targets for people with type 1 diabetes rather than type 2 diabetes?  Should the targets be different for older people than for younger people?  Are there dangers of pushing the HbA1c level too low?  This last question seemed to get a resounding "YES" as an answer when a study called the ACCORD trial was recently stopped because the people with type 2 diabetes who were in the group pushing to get their HbA1c as low as possible had worse cardiovascular outcomes (more of them had heart attacks and angina) than the group that kept their HbA1c levels a little higher.  The researchers were not able to prove that those bad outcomes were because the group attempting to get their HbA1c lower had more bad low blood glucose events (hypoglycemic attacks) and they couldn't tie it to a particular type of drug that those people were being treated with but it is still possible that those things (low blood glucose and particular drugs) were the cause of the extra bad heart outcomes.  We won't know until more larger research trial are finished.

Where does that leave you now?  I still think the best target for HbA1c is for you to try to keep it as close to the normal non-diabetic range as you possibly can without ruining your life with too much stress, expense, and problems like low blood glucosse levels and weight gain.  If you are older, or if you know that you already have coronary heart disease then a target for HbA1c between 7-8% is probably safer and better than one below 7.0% but no-one knows that for sure.  Whatever the target HbA1c level that you choose and that you achieve it is really important to do everything you can to reduce your risk of heart disease, anyway.  Don't smoke.  Eat a healthy diet.  Get regular exercise.  Get your blood pressure checked regularly and try to keep it below 130/80.  Talk to your doctor about whether you should be taking a statin drug, an ACE-inhibitor drug, and aspirin.  I talk about these things in more detail in the section of "Staying Healthy Longer" of The Diabetes Answer Book.  I'd be interested to hear what you think.

Is blood glucose testing a waste of time?

This may seem like an odd question to you but in the almost thirty years since home blood glucose testing has become widely available there has been a lot of debates between academic researchers on this topic.  A recent study came out suggesting that if you had type 2 diabetes you could get your average blood glucose level (as measured by glycosylated hemoglobin, or HbA1c) to the same level whether you tested your blood glucose or not.  I remember a similar study being done over twenty years ago to "prove" that self-blood glucose monitoring was "unnecessary" in type 1 diabetes.  In these studies people with diabetes were randomly divided into two groups.  Both groups were seen frequently by the research nurses and doctors and were encouraged to increase their pills and insulin to the maximum doses that could be tolerated without getting side effects, including low blood glucose levels (hypoglycemia).  The results of these studies has usually been that both groups of subjects end up at the same level of HbA1c which, to the researchers, "proves" that self-blood glucose testing is not necessary.

I do not agree with that interpretation of those studies.  It would be like dividing people into two groups and asking them to get through a dense forest on a pitch black night but only giving one group flashlights.  In truth, both groups would get through the forest eventually.  The group without the flashlights might take longer and would have more bumps and bruises from hitting unexpected trees, but they would all get through if they were persistent enough.  To me that does not prove that flashlights are unnecessary, however.

As you can tell if you read The Diabetes Answer Book I really like comparing blood glucose self monitoring to carrying a flashlight.  The whole purpose of using self-glucose testing is to allow you to know what your blood glucose is at different times of the day and night, before or after meals, and when you are feeling peculiar.  It "shines a light" on the situation to let you understand what is going on.  So whether you have type 1 or type 2 diabetes and whether you use pills or insulin or both to treat your diabetes a blood glucose monitor helps you to see how your blood glucose levels change in response to changes to treatment or to other things going on in your life.  I bet you that if any of those academic researchers got diabetes themselves they would prefer to do self-blood glucose testing rather than just blindly increasing their doses of pills and insulin until they got side effects or got hypoglycemia!

Like most tools that are available to us in life they are only useful if we know how to use them and how to interpret the results that they give us.

Scruffy, rude, bad-tempered, mystery adventures for the young at heart!

I am writing a series of adventure stories suitable for those aged twelve to adult featuring scruffy, rude, bad-tempered Scottish rock creatures called Gomes (NOT gnomes).  The first three of these will be published by Windstorm Creative, a wonderful publisher with a great philosophy, in the fall of 2008.  Windstorm Creative publish interesting and innovative books for people of all ages.  Check them out at:
www.windstormcreative.com

Although my "Gome Stories" are, like the Harry Potter books, aimed at a teenage audience I think they have appeal to all ages.  My older children are in their twenties and thirties and tell me that they really enjoy them, but maybe they are just saying that to be nice to me!  Each adventure is written as a trilogy of stories, each with twenty or so chapters and about 200-300 pages long.  The first trilogy is called Blackhope Scaur where the fast-paced action takes the heroes and villains from the alleys and waterfront of Seattle to the mountains of Scotland and ends up trying to save the citizens of Edinburgh from total destruction.  If you like humorous, fast-paced, adventurous nonsense as an escape from day-to-day worries about diabetes, or if you have teen or pre-teen kids who might like a new book to read you can check them out.

I have a blog that accompanies the series.  I describe the background to the stories and read the opening few chapters.  If you are interested at all you can check it out at:
www.gomeworld.typepad.com

Why I wrote the book

    I was approached and invited to write this book for a publisher called Sourcebooks, Inc.  Their website is www.sourcebooks.com .  They are publishing a series of books called "The Fill-in-the-blank Answer Book" on a variety of medical topics.  There is The Asperger's Answer Book, The ADD and ADHD Answer Book, The Anxiety Answer Book, The Autism Answer Book, The Bipolar Disorder Answer Book, The Menopause Answer Book among others, and I think there will be many more coming.  For each clinical topic they have invited someone who is a nationally recognized clinical expert to give straightforward answers to three hundred or so of the questions that he or she is most commonly asked by patients and their families.  I was honored to be invited to write about diabetes.  I have been working as a diabetes specialist physician (sometimes called a diabetologist) for over thirty years and have seen many thousands of patients during that time.  I love to try to make diabetes more understandable to people and I have learned a lot from my patients.

I had no trouble coming up with about two hundred questions that I am often asked.  I put them into four categories and sent the list of questions to a few dozen of my favorite patients as well as some of the doctors and nurses that I work with.  I asked them if there were other topics that they would like to see answers on.  That added over a hundred more questions.  I have no doubt that there are still quite a few topics that I have not thought of, but I do hope that the ones in the book are helpful to you.

If you have read The Diabetes Answer Book and find that you don't fully understand the answer that I have given, or if you want to ask a follow-up question, or if you have a new question that did not appear in The Diabetes Answer Book, I invite you to write to me at this blog.  I will read your questions and will post answers to some of the commonest and best questions that you come up with and share them with anyone else who reads this blog.

You may be able to buy The Diabetes Answer Book at your local bookstore.  If not you can buy it online at www.amazon.com or at www.sourcebooks.com

How diabetes has changed!

     To say that the management of diabetes has changed in the past thirty years is a major understatement.  It has been transformed.  when I became interested in diabetes as a medical student in Edinburgh in the 1970s there were only two types of pill to help lower the blood glucose.  The insulin we used contained impurities that could cause ugly scars where it was injected.  Patients used large glass and metal syringes that had to me taken apart and boiled once a week to keep them clean.  The needles were large and had to be sharpened on a carborundum stone when they got blunt.  The only way to have any idea what your blood glucose level was involved urinating into a test tube, adding a Clinitest tablet, and seeing what color it turned when it had finished boiling and frothing.  While this exciting spectacle may have appealed to our inner alchemist the information that it gave was about as useless as hanging seaweed out of the window and inspecting the color of that  few minutes later.  People with diabetes lived in constant fear of passing out from low blood glucose levels (hypoglycemia) or of developing awful complication of their disease.  The day-to-day burden on their lives was enormous.

The past three decades have seen many advances.  There are now many different types of pill to help lower blood glucose and to protect the kidneys, heart, and blood vessels from the ravages of diabetes.  Now we use highly purified analogs of human insulin that can be delivered using disposable pens and tiny needles.  You can carry little meters in your pocket that can give you an accurate blood glucose reading in a matter of seconds from just a drop of blood.  Other tests allow us to know how well diabetes is being managed overall and how healthy the heart and kidneys are.  Insulin pumps,  inhaled insulin, continuous glucose monitors, pancreas and islet transplantation have all become realistic treatment options for some patients.

Yet people with diabetes till live in fear of passing our from hypoglycemia or of developing awful complications of their disease.  The day-to-day burden of their lives is still enormous.  The proliferation of new and alternative treatments and the blizzard of information and misinformation on the Internet and other media make life more confusing than ever for people who have to live with diabetes.

In The Diabetes Answer Book and in the things I write in this blog I will try to demystify diabetes and give you common sense answers to many of the questions that I get asked every day.  I hope this will give you encouragement, confidence, and strength to make good choices for yourself about how you live your life and how you manage your diabetes.  There are likely to be many more amazing advances in the treatment of diabetes in the next few years.  Make sure that you stay healthy enough to take advantage of them.

You may be able to buy The Diabetes Answer Book at your local bookstore.  If not you can buy it on-line at www.amazon.com or at www.sourcebooks.com