Understanding hyperglycaemia in people with Type 2 diabetes

For people with Type 2 diabetes hyperglycaemia can be concerning. Here, we discuss what hyperglycaemia is, and how it can be avoided.


For people with Type 2 diabetes hyperglycaemia – when someone has high blood sugar levels – can be a cause for concern. Diabetes UK1 define hyperglycaemia as being blood glucose which is:

  • Over 7.0 mmol/l (over 126 mg/dL) when fasting
  • Over 8.5 mmol/l (over 153 mg/dL) 2 hours after meal

If left untreated and if blood glucose levels remain high over a significant period of time, it increases the risk of short- and long-term complications [hyperlink to long-term complications article on BL site]. Here, we explore what having hyperglycaemia means, how to spot it and how to avoid it.

What are the causes of hyperglycemia?

There are several reasons why you may have high blood glucose levels:

  • You may have missed a dose of your diabetes medication, or the dosage might not have been right
  • You may have eaten more carbohydrate than either your body or medication, or both, can cope with
  • You may have underestimated how much exercise you had planned to do (and any alterations in medications may not account for this)
  • You may be stressed
  • You may be unwell from an infection
  • You may have over-treated a hypo.

What are the symptoms of hyperglycaemia?

For people with Type 2 diabetes hyperglycaemia can be difficult to spot, especially when your blood sugar levels are only slightly higher than normal levels, and it can affect people in different ways. The following symptoms can be present in people who experience their blood sugar level rising to levels great than 10 mmol/l (180 mg/dL):

  • increased thirst and a dry mouth
  • needing to urinate frequently
  • tiredness
  • blurred vision
  • unintentional weight loss
  • recurrent infections, such as thrush, bladder infections (cystitis) and skin infections
  • tummy pain
  • feeling or being sick
  • breath that smells fruity

Treating hyperglycaemia

If you suspect hyperglycaemia, and if you have already been diagnosed with Type 2 diabetes, then you must check your blood sugar level as soon as possible. You should also contact your diabetes care team – your GP or diabetes nurse – and follow their advice. Depending on your current treatment plan, you may be advised to monitor your blood sugar levels more frequently, and they may also offer you additional diet and lifestyle advice to help lower your blood sugar levels. Depending on your blood glucose level, you may be advised to test your blood or urine for ketones as well – a substance that is associated with diabetic ketoacidosis (DKA).

What is diabetic ketoacidosis (DKA)

When there are insufficient levels of insulin in the body, it means that the body cannot use sugar for its energy. The body then starts to use fat as its energy source and, as a by-product of the breakdown of fat, ketones are released. If left unchecked, ketones can start to build up in the blood and become acidic, which can become dangerous. And this is known as DKA. While DKA can affect people with Type 1 diabetes, it can also affect people with Type 2 diabetes. The symptoms of DKA are similar to those listed above for hyperglycaemia, and they can appear quite rapidly, so quick action is needed to prevent further deterioration.

DKA is treated as a medical emergency because it needs to be sorted out immediately or it can be highly dangerous – and in some cases, fatal. If you or someone you know with diabetes experiences any of the signs of ketoacidosis, get medical help straight away.

How to avoid hyperglycaemia and DKA

Taking your medication correctly and monitoring your blood sugar levels regularly can help avoid hyperglycaemia and DKA.

It’s not uncommon for your blood sugar levels to be higher than normal when you are unwell. You should work with your healthcare team to come up with some sick day rules for when you are ill. You should stay hydrated and eat little and often. If you take diabetes treatment called SGLT2is, and if you become unwell, you should stop taking these tablets. Continuing to take them when you’re ill can increase your risk of DKA. Also, when you are unwell, if you take insulin then checking your blood sugars more than you would usually, can help keep your blood glucose levels in check.

Frequently asked questions

1. How can I avoid hyperglycemia?

Exercise is one of the best and most effective ways to prevent your blood sugar level rising, and to avoid hyperglycaemia. If you have any complications that are a result of blood vessel injury – such as nerve, foot or eye damage – then first discuss an exercise plan with your GP.

2. Can drinking a lot of water help keep my blood sugar levels low?

No. Feeling thirsty is a symptom of hyperglycaemia and while drinking may address this symptom and rehydrate you if you are dehydrated, it will not affect your blood sugar levels. If you regularly have high blood sugar levels, then contact your diabetes healthcare team.

3. I feel anxious when I get a high blood sugar level reading; what can I do about this?

It’s very common for people with Type 2 diabetes to feel worried, sad or frustrated if they get a high blood sugar level. But it is important to get help if you regularly feel like this. Talking to friends and family about how you feel and how they can help you is a great first step. Also, your diabetes care team can help with the emotional side of managing your Type 2 diabetes as well as the physical side. They recognise that this is as equally important and are keen to support and advise you.