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It seems rare people discuss why your fasting glucose levels may be high. Instead, most attention in type 2 diabetes is paid to diet and the effect of food on your glucose levels. It’s something I’ve talked about on this blog frequently including such articles looking at your diet that you can find here.

What we pay less attention to is why your fasting levels might be elevated. Despite the fact many of you reading this will have experienced this. However, there are some very good reasons you might see high fasting glucose levels which I wanted to discuss today.

The progression of your diabetes

It’s important to put your glucose levels into context. A fasting glucose above 7mmol/l is diagnostic of type 2 diabetes. Lots of you will wake with normal or near levels in the morning. However, there will also be lots of you with fasting glucose levels well into the teens and even higher sometimes. This isn’t particularly too uncommon with the cohort of patients I see regularly in the hospital.

Your glucose levels should be roughly between 4mmol/l to 7.8mmol/l depending on when you test your levels (they may be higher if you test quick enough after meals). Ideally your fasting glucose levels should be below 6mmol/l to register in the normal range. Therefore, if you are seeing levels above this, physiologically, this isn’t normal. It shows something inside you isn’t working as it should.

The further away you get from normal levels, the more your diabetes is likely to have progressed. This makes sense really, higher glucose levels indicate a bigger problem. Some people can live with type 2 diabetes for up to 10 years without realising before being diagnosed. These people will have had some disease progression before even knowing they have a problem.

Of course, we can add in medications to help this and these may very well resolve the problem. This doesn’t mean your diabetes has gone away. New medications will help lower your glucose levels but each new medication represents a progression of the disease. If it’s age related and you’re in your 70’s and 80’s I wouldn’t worry too much. However, if you’re in your 40’s or 50’s and you’re already being given multiple diabetes therapies, this is a sign the situation is worsening. Serious lifestyle change at this point is recommended.

The Liver

The liver is the major player in why your glucose levels rise overnight. The liver is responsible for storing and releasing glucose into your blood stream between meals and when you need a top up of glucose.

Usually, this is a tightly controlled process where only what you need is released. Insulin usually tells the liver to turn off its release of glucose when there’s enough in the blood.

In type 2 diabetes most patients will also have some form of fatty liver too. Therefore the liver becomes resistant to insulin’s message and continues to release glucose even when levels are running high.

As a result, your baseline glucose level is higher than what is should be. This can be particularly pronounced with your fasting glucose level.

This is one reason lifestyle change is very effective in managing type 2 diabetes. Shedding fat around the liver helps to lower your morning and overall glucose levels.

If you want a more detailed overview of how the liver effects your glucose levels, I’ve done a blog about it here.

The impact of Hormones

Hormones can have an impact on your fasting glucose levels. Hormones like cortisol and growth hormone are released in the morning to get your body ready for the day ahead. These also increase glucose levels.

Usually your body counteracts these by releasing some insulin to help keep your glucose levels within a tight bandwidth. In type 2 diabetes, insulin is being released but it’s not working very well. This leaves your glucose levels susceptible to rising above normal levels.

This can be difficult to control but it still represents an inability of your body to control its own glucose levels. Without diabetes, your fasting glucose levels would not go high at any time throughout the day. Therefore, this too represents a progression of the disease.

Bedtime glucose levels

Your evening meal will ultimately dictate how high your glucose level go above your pre meal reading. The food itself won’t effect your fasting glucose level in the morning because the food will be absorbed and dealt with by then in most cases.

One thing to consider though is how high your glucose levels went after the meal. A glucose test before bed can help us understand the morning level. If your glucose level is high before bed it has a long way to travel to fall back into normal ranges in the morning.

For example, if you wake with a fasting glucose of 11mmol/l, this is high. However, if you went to bed with a glucose level of 21mmol/l, it’s more likely the high morning reading is due to the evening meal. Especially, if your pre meal test was 11mmol/l – and so it’s increased by 10mmol/l after eating.

This opens another topic about why your glucose levels are going so high after meals. However, it’s the same principle. Your diabetes is progressing and your body is struggling to regulate it’s glucose levels as it should.

I understand many of you won’t be testing your glucose levels more than once per day. If you do have glucose test strips it might be a good idea to do some tests throughout the day to help understand your glucose levels in more detail. Typical times to do this is pre meals and before bed.

You can then start to identify the times of day when problems might be emerging.


As you can see there are lots of reasons you have high fasting glucose levels. Ultimately, the further away from normal your glucose level become, the worse the diabetes is progressing. If you haven’t done so already, now is the time for getting as healthy as possible. Looking at your diet and exercise habits go a long way to help achieving this.

If you need a helping hand, check out my type 2 diabetes recovery programme, which is a step by step guide about how to do it.

I’ll see you next time.

Need more help

If you need more support we offer a range of 1:1 consultancy services and online programmes focused on helping you improve your glucose control and health for the long term. These include our type 2 diabetes recovery programme, type 1 glucose stability programme and winning weight loss programme. Go to the pages using the links above or in the headers or get in touch if you have questions.

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