The T2 "You don't need to test" Myth.
There were 2 studies published in 2007 and 2008 which appear to be used as the main justification for the claim "you don't need to test" in relation to Type 2 diabetics. These studies were both flawed in this reasoning and their conclusions incorrect.
The DIGEM study published in 2007 by Farmer et al started out with the objective of using Self Monitoring of Blood Glucose (SMBG) to reinforce the prescribed dietary advice, using 3 BG readings each on 2 days per week. However the patients were told not to change their diet because of the results they obtained and were encouraged to stick more rigidly to the prescribed diet.
"They were also given training and support in timing, interpreting, and using the results of their blood glucose test to enhance motivation and to maintain adherence to diet, physical activity, and drug regimens" [1]
However, because the HbA1c of the patients did not improve as a result of testing, their conclusion was that SMBG does not help to lower HbA1c.
This is a flawed conclusion.
It merely demonstrates that getting patients to test while instructing them to do nothing about the major cause of high BG (meal choices) does not help reduce HbA1c. The patients were told not to change anything, but to stick more rigidly to what they were already doing. It appears to be rather obvious to most laymen that simply recording data while preventing any change to the underlying causes does not help to reduce problems.
Since no change was observed in relation to the HbA1c of the patients in the study, it would appear to demonstrate that the prescribed diet does not help reduce HbA1c. This is not surprising. The dietary advice from the British Dietetic Association, echoed by Diabetes UK and other organisations is to base meals on starchy carbohydrates. Since carbohydrates raise blood glucose levels and as a result, contribute to the HbA1c this dietary advice is clearly not designed to reduce HbA1c.
The ESMON study published in 2008 came to the same flawed conclusion as the DIGEM study, but for different reasons. It also concluded that SMBG increased rates of depression in patients.
Their method can be seen from this quote:
"They were asked to monitor four fasting and four postprandial capillary blood glucose measurements each week. They were advised on appropriate responses to high or low readings. Such advice included the need for dietary review or the suggestion of exercise (such as walking) in response to high readings." [2]
Notice that there were 4 fasting and 4 post-meal readings. Unless the post-meal readings were all at breakfast, there is no relationship between the before and after BG of a meal. The post prandial readings were then likely to be unrelated to anything else and if the BG was high before the meal, this would tell the patient nothing about the cause of the high BG. As any scientist or statistician knows full well, a single spot check proves nothing.
Also, because of the unpredictable nature of Dawn Phenomenon, a fasting reading on its own demonstrates very little.
Also due to the reliance on dietitians in other areas of the study's methodology, it would appear that "dietary review" involved discussion along the lines of reinforcing the prescribed dietary advice.
How the patient is supposed to gauge the effects of exercise based on a post prandial BG, unrelated to the exercise session without any readings before or after the exercise itself is not explained. Presumably this was to reinforce the slight difference to BG made by exercise for the following 48 hours, although this can be wiped out by unwise dietary choices.
So again, this study was attempting to reinforce the standard dietary advice, which is not aimed at reducing HbA1c.
The reason for the increased levels of depression then is easily explained. When these patients obtained out of range BG readings, they undertook dietary review, reinforcing a diet which is not aimed at reducing BG levels which then did not help to reduce BG. So the patients were sticking more rigidly to their dietary plan, more rigidly to their medical advice and failed to see any improvement. Then they got depressed.
One respondent to the BMJ site on this topic recommended the study for a "no s**t sherlock" award.
The method of SMBG recommended by diabetics across the world via the web is usually summarised by Jennifer's Advice:
http://www.diabetes-support.org.uk/joomla/jennifers-advice
Increasingly, it appears, people are also recommending pre-meal BG readings to compare with the post-meal readings in order to see the change in BG rather than absolute numbers. This gives a better indication of the effect of the meal.
The important thing about this approach is the emphasis on learning from those BG readings to govern future food choices. As time progresses the patient learns more about the effects of food. But the more intensive the testing, the more effective the process. Using SMBG a couple of days per week is not effective since the patient does not learn anything the rest of the time and may be elevating their BGs as a result of unwise dietary choices.
Key to the control of BG, as shown by all those who have used Jennifer's Advice is the control of carbohydrate intake. This does not specifically mean carbohydrate avoidance, but a tailoring of the diet to the quantities and types of carbohydrates which can be tolerated by the individual.
Over 6 years I have seen a great many Type 2 diabetics try Jennifer's Advice and achieve massively improved HbA1c results. I have not seen any patient who has given it a serious try, who did not have an improved HbA1c.
Perhaps someday, a researcher will bother to ask a well controlled Type 2 how to study the effects of SMBG. The study would then involve more intensive testing with a premeal test and both 1-hour and 2-hour postprandials. There would be groups which performed this level of testing for 1,2 or 3 meals per day and a group which also did additional tests at other times. The study would obviously show an improvement in HbA1c over a 3 month period - better still 6 months to allow the patients to learn and improve from that learning. From the results of such a study it would be possible to work out the most cost-effective way of helping patients to self-educate over a period of months
So in summary, these two studies do NOT prove that SMBG does not work. It proves instead:
1) The specific methods and purposes of SMBG used in the DIGEM and ESMON studies do not help to lower HbA1c
2) The prescribed diet based on starchy carbohydrates does not help to reduce HbA1c.
References:
[1] DIGEM Study http://www.bmj.com/cgi/content/full/335/7611/132
[2] ESMON Study http://www.bmj.com/cgi/content/full/336/7654/1174
