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Complications of type 1 diabetes

Last month we looked at the management of type 1 diabetes in terms of symptoms and the types of insulin used. Here we turn our attention to disease complications and how pharmacists can support patients living with the condition.

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:

  • Sweating
  • Feeling anxious
  • Drowsiness and tingling lips
  • Palpitations
  • Hunger
  • Trembling/shaking. 

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’

Manage blood glucose levels

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.

Ensure adequate calorie intake and hydration with fluid replacement

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.

Test for ketones

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.

Recognise when further medical attention is required

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 

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

These include:

  • High blood sugar levels
  • Being very thirsty
  • Polyuria
  • Feeling tired and drowsy
  • Confusion
  • Blurred vision
  • Abdominal pain
  • Nausea or vomiting
  • Sweet or fruity-smelling breath (like nail polish remover or pear drop sweets)
  • Fainting.

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.

Cardiovascular disease 

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

Lipid targets

> 40% reduction non-HDL cholesterol from baseline

Blood pressure targets (mmHg)

< 135/85

If albuminuria or ≥ 2 features of metabolic syndrome present, then < 130/80

In those ≥ 80 years = < 150/90

Living with type 1 diabetes

Although there are no dietary restrictions, patients with type 1 diabetes should be encouraged to follow a healthy diet comprising food from all food groups. The Diabetes UK top healthy diet tips include: 

  • Choose healthier carbohydrates such as whole grains (e.g. brown rice, buckwheat and whole oats), fruit, vegetables, pulses (e.g. chickpeas, beans and lentils) and dairy (e.g. unsweetened yoghurt and milk)
  • Eat less salt
  • Eat less red and processed meat
  • Eat more fruit and veg
  • Choose healthier fats (e.g. unsalted nuts, seeds, avocados, oily fish, olive oil, rapeseed oil and sunflower oil)
  • Cut down on added sugar
  • Drink alcohol within recommended limits.

Patients with type 1 diabetes can drive but they need to inform the DVLA that they are on insulin. This applies to both group one and group two drivers. 

Glucose levels should be checked via the patient’s usual method before driving and every two hours if on a long journey. Hypo treatments must be easily accessible. The glucose readings need to be above 5mmol/L to drive. 

If the patient feels a hypo is coming on, they should stop the vehicle in a safe place, the engine should be switched off, the keys removed from the ignition and the patient should move over to the passenger seat. This procedure must be done to show the patient is not in charge of the car while they are having a hypo. 

The hypo should be treated (see hypoglycaemia section) and following this, the patient should wait for 45 minutes before they start driving again. 

Rules pertaining to group two drivers are more stringent and they should be advised to check the DVLA site for further information. 

Those using rtCGM or isCGM/Flash systems will need to confirm the hypo using the conventional method of finger-pricking once they have parked their vehicle in a safe place and treat the hypo once it has been confirmed by the blood glucose meter.

Although patients with type 1 diabetes are exempt from fasting, the EPIDIAR study found that 43 per cent of patients fast irrespective of any advice given to them. Patients with type 1 diabetes are at increased risk of ketoacidosis – particularly if their diabetes is poorly controlled before Ramadan – as well as dehydration and thrombosis. 

Patients wishing to fast should ask for advice on managing insulin doses during Ramadan. 

Although travelling with type 1 diabetes can be challenging, it is not limiting. Increased awareness of varying glucose levels is required especially if going on a very active holiday or to places where the weather is hot or cold, so regular testing is advised. It is also advisable to keep insulin and hypo treatments in hand luggage for easy access and to prevent it from freezing if stored in the hold.

Timing of insulin doses may need to be adjusted if travelling to or through different time zones. For instance, if the time difference is less than four hours from UK time, insulin should be injected at the patient’s usual times. If the time difference is greater than four hours from UK time, consideration will need to be taken on how to manage insulin injection schedules. The patient should be advised to discuss their journey with their diabetes care team. 

Patients with type 1 diabetes can exercise and do sports safely, but they must balance their insulin doses, food intake and blood glucose levels. Exercise can help reduce insulin resistance and hyperglycaemia, but it can also cause hypoglycaemia if not managed properly. It is important that glucose levels are checked before exercise and managed accordingly.

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