What are highs and lows?

What are highs and lows?

Recognise your highs and lows

As you may already know, there are several factors that can cause changes in your blood glucose levels, such as your diet, how much exercise you take and treatment. 

Despite your best intentions factors out of your control, such as if you get ill or feel stressed, can also affect your blood glucose levels.

Food can rapidly affect blood sugar

Stress & illness can cause your body to be less sensitive to insulin

Physical activity tends to lower blood sugar

Medication can directly impact blood sugar: dose, timing, interactions with non-diabetes medication

The changes in your blood glucose levels may not be your fault, which is why it’s important to discuss these factors with your healthcare professional. Even the smallest adjustments to your diabetes management may be able to help you better control your blood glucose levels on a day-to-day basis.

Take a look at the handy Diabetes UK checklist to help you assess your highs and lows, and identify topics for discussion with your healthcare professional.

Symptoms of high blood glucose and low blood glucose

If your blood glucose level climbs too high, you may experience symptoms of hyperglycaemia, which may include:1

Increase in urination

Increased thirst

Increased heart rate

Increased tiredness

Hyperglycaemia can be caused by simple things, like eating too much food, drinking too many sugary drinks, getting too little exercise, not taking medicine appropriately, illness or stress.1 The best way to know for sure whether or not you have hyperglycaemia is to check your blood glucose level.1

If your blood glucose level falls too low, you may experience symptoms of hypoglycaemia, which may include:2

Increased hunger

Feeling sweaty

Feeling shaky

Feeling dizzy

While symptoms of hypoglycaemia can vary from one person to another, there are some common signs you should be aware of. These symptoms of low blood glucose can include anxiety, weakness, confusion, shakiness, sweating, feeling tired, hungry or nervous.1 If you’re experiencing any symptoms of low blood glucose, you should take some fast-acting carbohydrate, for example a sugary drink or some sweets/glucose tablets, followed by some longer-acting carbohydrate, such as a piece of bread or biscuits. Once you have stabilised your blood glucose level, you should speak with your healthcare professional about what additional actions you could take to help avoid future hypos.

How to treat hyperglycaemia and hypoglycaemia

Stabilising your blood glucose can make a big difference. Here are some things you can do when your blood glucose levels are too high or too low:

  • Work with your healthcare professional to adjust your meal plan or physical activity
  • Talk to your doctor about adjusting your medicines
  • Talk to your healthcare professional about what a high or low blood glucose level is for you and when you should contact them

If you are concerned, you can use the Diabetes UK checklist to help you to look at your highs and lows.


Ask your doctor what blood glucose range is right for you. The HbA1c target for most people with type 2 diabetes is 48 mmol/mol (or 6.5%), but your doctor might suggest a different target for you.3,4

To minimise your risk of long term problems caused by blood glucose levels that are higher than normal, you should aim for the following target levels:3

  • between 5 and 7 mmol/litre before breakfast ('fasting' level)
  • between 4 and 7 mmol/litre before meals at other times of the day

If you have to test after a meal, the target level at least 90 minutes after eating is between 5 and 9 mmol/litre.3

Your diabetes care team should talk with you about your blood glucose targets. This includes what level to aim for before you go to bed, which will depend on both when you last ate and on your medication, including, if used, your insulin dose.3