Glucose targets is one of the most important topics I cover with my patients because it is the foundation of how we manage their diabetes.
Let me me ask you a question. Have you ever been told your glucose target should be between 4-7mmol/l? If I had £1 for every time someone gave me this answer I’d be long on a Caribbean island sipping Mojitos. This is the text book answer of course and would also translate into great control. If you have managed to keep them in this range then credit to you. However, for many patients this sets an unrealistic target. This results in many frustrated patients because they are seemingly unable to control their glucose levels. This is particularly risky in type 1 diabetes where patients are prone to episodes of hypoglycaemia.
Please do not think I am having a go at the patients either. In fact, the complete opposite is true. If you have been told this is your target I think the concept of diabetes and blood glucose levels hasn’t likely been explained to you in detail. This is often due to time pressures but also can be due to an underlying misunderstanding of how blood glucose levels behave in diabetes.
How can the same glucose target apply regardless of whether you are 18 or 80 years old? No, glucose levels need to reflect your own circumstances and lifestyle
But enough of the intro, lets get into how you should be setting your glucose level targets.
Why 4-7mmol/l glucose targets?
It is thought people without diabetes glucose levels will remain between 4-7mmol/l. Remember though, diabetes is a condition effecting how well you can control your glucose levels. Setting targets to the same level as someone without diabetes is probably unrealistic. Particularly in type 1 diabetes. Granted medications can help bring down the levels to within or near 4-7mmol/l in some people but this can be tricky.
In reality glucose levels will go above 7mmol/l quite regularly. After meals even people without diabetes can see rises above 10mmol/l. BUT these levels will quickly drop back between 4-7mmol/l typically 1-2 hours after the meal. This is why some diabetes tests check blood sugars 2 hours after doing a glucose tolerance test.
I have even tested my own glucose levels 30 minutes after lunch and recorded a value of 9.4mmol/l.
So giving targets of 4-7mmol/l needs to come with one large caveat. Glucose levels should be 4-7mmol/l 2 hours after eating or before meals assuming no snacks have been eaten in between.
In practice there is little additional benefit between targets of 4-7mmol/l and 4-9mmol/l. Readings between 4-9mmol/l will also give you pretty good control and gives more realistic ranges to play with. It gives more flexibility to the patient. Puts less pressure on them and therefore may be a more suitable target.
It’s important to think practically with these targets. For example, if you test only once daily before breakfast and have a reading of 9mmol/l, yes it’s within target, but it will go up after eating. In fact, unless taking insulin with meals, it’s likely the lowest it will be all day. In this case you might want to consider ways to reduce this morning result.
Therefore, the 4-7mmol/l rule is more for tests first thing in the morning and before meals. Basically 4-7mmol//l is for fasting results.
Is HbA1c is a better glucose target measure?
HbA1c is the test your GP will take at your diabetes review. This gives you an average of your previous 3 months of glucose readings. It does this because glucose sticks to your red blood cells and these last 3 months before dying off.
One negative of this test it does not pick up swings in glucose levels. This can happen with insulin users and can produce good HbA1c results despite frequent highs and lows because it’s an average.
Some people won’t need to test glucose levels at home. Generally, we only give testing equipment to people who take medications which can push their glucose levels too low. People not testing will solely rely on the HbA1c to gauge their control.
Those testing daily glucose levels will not capture the whole picture. Each test only represents the here and now. Although useful information, particularly in type 1 diabetes, the HbA1c result is still a better gauge of overall control.
HbA1c glucose targets set by the national institute for health and care excellence (NICE) are between 48-59mmol/mol. Levels between these values put you at no greater risk of developing complications. The higher your levels rise above this the more at risk you become of developing complications.
Time in target
In more recent years patients with type 1 diabetes can be prescribed continuous glucose or flash glucose monitors by their GP surgery. This usually follows an intensive period of education and work with their diabetes team. People with type 2 diabetes can also purchase these but cannot currently get them on prescription.
The continuous glucose monitors or CGM’s like the DEXCOM track glucose levels over a 24 hour period and provide insights into glucose data that previously was impossible to see.
The Freestyle fibre achieves the same result but needs to be scanned or flashed every 8 hours as a bear minimum.
These devices are great because they give data about time in target, above target and below target. This is more valuable than the HBA1c result because we are no longer relying on an average glucose level. If 2 people have the same HbA1c result but one of them swings between 20mmol/L and 3mmol/L all day and the other person achieves a steady 5-9mmol/L, we can now see this.
Healthcare teams are now using time in target much more than just replying upon HbA1c.
What readings should I be targeting?
This is my reason for the article. Diabetes healthcare professionals want to reduce your risk of developing diabetes related complications. If you do not develop complications and are not symptomatic it doesn’t really matter you have diabetes.
The problem is most people with persistently high or low glucose readings do develop complications.
Targets need to be realistic for you. Aiming for a range i.e. 5-10mmol/l rather than single number targets is much more realistic because glucose levels are always changing.
Someone diagnosed with diabetes at 28 years old, in theory, has a lot of years to live with diabetes. Therefore, glucose targets will be tighter in this patient. Possibly closer to the 4-7mmol/l target.
Someone diagnosed with diabetes at 75 years old will have less risk of developing complications than their 28 year old counterpart. We would tend to relax the glucose targets in this individual. Possibly 5-12mmol/l. Someone who has a complex medical history may even see their targets even further relaxed.
NICE recommends glucose targets should be individualised with patients. This should consider all circumstances but in the majority of people 48-58mmol/mol will be appropriate.
Recently diagnosed glucose targets
Those recently diagnosed with type 2 diabetes can benefit from a ‘legacy effect’ if they keep good glucose control upon diagnosis.
The UKPDS study in 1998 split patients into two groups – intensive glycaemic control and diet alone. The difference in glucose control as measured by HbA1c between groups was actually quite modest. The intensive group maintained an average HbA1c of 53mmol/mol compared to the diet alone group of 63mmol/mol throughout the study. Despite this modest reduction, the intensive glucose control group had a 25% reduction in vascular disease and saw reduced disease progression.
Once the study finished the HbA1c difference between the groups evened out. Despite this the tightly controlled group had a better level of health and quality of life when followed up 10 years later. Hence the ‘legacy effect’.
Therefore, good glycaemic control is important at this stage.
Over treating is a problem
Most patients will have a good management plan in place. Some patients though are being over treated. This is usually the result of someone remaining on the same therapy for a number of years despite their circumstances changing.
This is common in the elderly. Often we see patients admitted to hospital taking too many medications. I’ve had 80 year old patients still aiming for a target of 4-7mmol/l because they were told that is their target 45 years ago. Predictably some of these patients suffer with frequent hypoglycaemia.
Of course, this places the patient at risk. This is particularly important with elderly patients taking insulin.
Elderly patients are less likely to suffer the long term complications of diabetes. Therefore, it is always worth checking with your medical teams to see if treatment can be reduced in such circumstances.
Quality of life can sometimes be as big a consideration as medication. A trade off exists between the medicine burden and the benefit of that medication. Reducing the number of medications can sometimes have a positive effect on patients quality of life.
Glucose targets should be set for each patient. I would encourage you to set targets with your healthcare teams. Whether aiming for NICE targets, better or more relaxed control is your goal, please establish a target. This then gives you a base to aim for.
Type 1 diabetes patients may want to increase their bottom line target to 5mmol/l because they are prone to hypoglycaemia. Increasing the bottom line target leaves more margin for error.
In this article I must state I am not referring to gestational diabetes. This has it’s own individual targets and these should be set alongside your healthcare team.
Consider your age, type of diabetes, potential years to live with the condition, your individual circumstances and ultimately what is right for you. Realistic goals can then be set from the start and help you manage your diabetes better over the long term.