One of the main complications of type 1 diabetes is hypoglycaemia. A ‘hypo’ can occur for a number of reasons, including if too much insulin has been injected, a meal has been missed, consumption of starchy foods has reduced, insulin has been injected incorrectly, alcohol consumption has increased or alcohol has been drunk without food intake, or unplanned strenuous exercise has been undertaken.
Hypoglycaemia is defined as when blood glucose levels drop below 4mmol/L. The symptoms of hypoglycaemia include:
- Feeling anxious
- Drowsiness and tingling lips
When treating hypoglycaemia, the aim is to raise blood glucose levels quickly. Around 15-20g of quick acting carbohydrates should be taken (e.g. 200ml of orange juice, 150ml full sugar cola drink, 60ml GlucoJuice, five GlucoTabs, six dextrose tablets or four jelly babies).
The treatment can be repeated after 10-15 minutes if the blood glucose level is still less than 4mmol/L. Once the hypoglycaemia has been successfully treated, and it is not yet a mealtime, patients should be advised to eat some starchy foods such as two plain biscuits, a small banana or two slices of toast.
‘Sick day rules’
Blood glucose levels can rise during illness, even if the patient is not eating, so it is necessary to increase blood glucose monitoring. Doses of insulin may need to be increased during illness, especially if ketones are present (see section on diabetic ketoacidosis).
It is important to note that insulin should not be stopped, even if the patient is not eating anything. Insulin doses should be guided by the person’s glucose levels.
It is important to maintain regular hydration and carbohydrate intake. However, if the patient is not able to eat or is vomiting, they should be advised to replace meals with sugary fluids. If blood glucose levels are high, fluid intake should be maintained with sugar-free fluids.
Ketones should be checked every four to six hours and, if present, every two hours. Extra rapid-acting insulin doses in addition to regular doses should be taken depending on the blood glucose levels. It is pertinent to drink plenty of water to maintain hydration and flush through the ketones.
If vomiting or unable to keep fluids down, or unable to manage either blood glucose or ketone levels, medical advice should be sought as soon as possible. It is important to advise the patient to reduce their insulin back to normal once the illness resolves.
Some drugs need to be stopped during periods of acute illness and restarted within 24-48 hours of eating and drinking normally. These include ACE inhibitors, ARBs, diuretics, NSAIDs, metformin (unlicensed use), SGLT2i (unlicensed use) and GLP-1RA (unlicensed use).
Diabetic ketoacidosis (DKA) is a serious condition which arises when there is a severe lack of insulin in the body to allow the glucose to enter the cells. This lack of availability of glucose leads to fat being broken down for energy, producing ketones, which can make the blood become acidic (see panel opposite for the signs and symptoms of DKA).
In the presence of these symptoms (see below)or during periods of illness (see ‘sick day rules’ section), the patient should check their blood glucose and blood ketone levels. All patients with type 1 diabetes should be provided with a blood ketone monitor even if they are using real-time continuous glucose monitoring (rtCGM) or intermittently scanned continuous glucose monitoring (isCGM), commonly known as Flash. See ‘sick day rules’ on how often blood ketones should be checked.
Signs and symptoms
- High blood sugar levels
- Being very thirsty
- Feeling tired and drowsy
- Blurred vision
- Abdominal pain
- Nausea or vomiting
- Sweet or fruity-smelling breath (like nail polish remover or pear drop sweets)
Understanding blood ketone levels
- Less than 0.6mmol/L is normal
- 0.6 to 1.5mmol/L means there is a risk of developing DKA; ketones should be tested again after two hours
- 1.6 to 2.9mmol/L means there is a risk of DKA: the diabetes team or GP should be contacted as soon as possible
- 3mmol/L or higher means there is a very high risk of DKA and emergency help should be sought as soon as possible.
Patients with type 1 diabetes are two to five times more likely to develop cardiovascular disease (CVD) compared to people without diabetes. This may be due to continuously raised glucose levels. Statin treatment should therefore be offered for the primary prevention of CVD to adults with type 1 diabetes who:
- Are older than 40 years
- Have had diabetes for more than 10 years
- Have established nephropathy
- Have other CVD risk factors.
Blood pressure should also be maintained to reduce the risk of CVD and CKD. Table 1 lists the target ranges for lipids and blood pressure recommended by NICE.
Table 1: Target ranges for lipids and blood pressure from NICE
> 40% reduction non-HDL cholesterol from baseline
Blood pressure targets (mmHg)
If albuminuria or ≥ 2 features of metabolic syndrome present, then < 130/80
In those ≥ 80 years = < 150/90