Hyperglycemia, or high blood sugar, is defined as blood glucose levels greater than 7 mmol/L when fasting or greater than 11 mmol/L two hours after meals. It can be caused by issues with insulin production or resistance. Symptoms of hyperglycemia include increased urination, thirst, and hunger. Left untreated, it can lead to serious short-term complications like diabetic ketoacidosis or long-term complications affecting organs. Hypoglycemia is low blood sugar below 4 mmol/L and symptoms include sweating, weakness, and confusion. It is treated with fast-acting carbohydrates. The document provides guidelines on diagnosing and managing hyperglycemia, hypoglycemia, and ketoacidosis

1. Medical Decisions Unit
August 2016 1
Cambridge University Hospitals

2. Hyperglycaemia, the term for expressing high blood
sugar, has been defined by the World Health
Organisation as:
 Blood glucose levels greater than 7.0 mmol/L (126
mg/dl) when fasting
 Blood glucose levels greater than 11.0 mmol/L (200
mg/dl) 2 hours after meals
Although blood sugar levels exceeding 7 mmol/L for
extended periods of time can start to cause damage to
internal organs, symptoms may not develop until blood
glucose levels exceed 11 mmol/L.

3. The underlying cause of hyperglycaemia will usually be
from loss of insulin producing cells in the pancreas or if
the body develops resistance to insulin.
More immediate reasons for hyperglycaemia include:
 Missing a dose of diabetic medication, tablets or
insulin
 Eating more carbohydrates than the body and/or
medication can manage
 Being mentally or emotionally stressed (injury,
surgery or anxiety)
 Contracting an infection

4.  The main 3 symptoms of high blood sugar levels
are: increased urination, increased thirst and
increased hunger.
 High blood sugar levels can also contribute to
the following symptoms:
◦ Regular/above-average urination
◦ Weakness or feeling tired
◦ Loss of weight
◦ Increased thirst
◦ Vision blurring

5. Hyperglycaemia can be serious if:
 Blood glucose levels stay high for extended
periods of time - this can lead to the
development of long term complications
 Blood glucose levels rise dangerously high -
this can lead to short term complications

6.  Ketoacidosis is a dangerous complication that mainly
affects people with type 1 diabetes but can also affect
some people with type 2 diabetes that are dependent
on insulin. The risk of ketoacidosis becomes
significant if blood glucose levels rise above 15
mmol/l (270 mg/dl).
 There is a higher risk of ketoacidosis if a dose of
insulin is missed or during periods of illness.
 A dangerous complication known as hyperosmolar
hyperglycaemic nonketotic syndrome can affect
people with diabetes if blood glucose levels remain
very high, above 33 mmol/l (600 mg/dl) for an
extended period of time.

7.  Regularly having high blood glucose levels for long
periods of time increases the risk of organ damage
occurring which can lead to health problems that are
commonly referred to as the long term complications of
diabetes.
 HbA1c target of 48 mmol/mol (6.5%) will reduce the
chances of developing diabetes complications.
 The most widely reported long-term diabetes
complications include:
 Heart disease
 Diabetic retinopathy
 Nephropathy
 Neuropathy

8.  Diabetic ketoacidosis (DKA) is a complex disordered
metabolic state characterised by hyperglycaemia,
acidosis and ketonaemia.
DKA is defined by the triad of:
blood glucose of >11mmol/L
pH <7.3 and/or bicarbonate <15mmol/L
blood ketones of >3mmol/l
Please note: Urine ketones are not reliable and a
finding of positive urine ketones must be followed up
by a blood ketone check as per guidelines for ketone
testing for adult in-patients with diabetes mellitus

10.  Two consecutive 4-hour blood glucose levels are
above 13mmol/L or One reading is above 17mmol/L
especially if the patient is unwell or exhibiting
symptoms/signs associated with ketosis such as
Abdominal pain
Nausea and/or vomiting
Breathlessness
Breath that smells fruity/pear drops/acetone
General deterioration in health
 Continue regular 2-hourly ketone monitoring till
ketones are <0.6 for two consecutive tests

13.  Hypoglycaemia occurs when blood glucose levels fall below 4 mmol/L (72mg/dL).
Signs and symptoms:
 Sweating
 Fatigue
 Feeling dizzy
 Palpitations/anxiety
 Being pale
 Headache/nausea
 Feeling weak
 Feeling hungry
 Blurred vision
 Confusion/mood change/irritability/aggression
 Poor co-ordination/ difficulty speaking/ lack of concentration
 Convulsions
 Loss of consciousness
 Seizures
 And in extreme cases, coma

14. Whilst low blood sugar can happen to anyone, dangerously
low blood sugar can occur in people who take the following
medication:
 Insulin
 Sulphopnylureas (such as glibenclamide, gliclazide,
glipizide, glimepiride, tolbutamide)
 Prandial glucose regulators (such as repaglinide,
nateglinide)
Factors linked to a greater risk of hypos include:
 Too high a dose of medication (insulin or hypo causing
tablets)
 Delayed meals
 Exercise
 Alcohol

15.  Medication related:
◦ Prescription errors – wrong insulin, wrong dose or wrong time.
◦ Administration errors - mismatch in insulin and meal times.
◦ Mismanagement of VRIII – lack of appropriate monitoring or lack
of substrate (dextrose or artificial feed).
◦ Inappropriate use of PRN doses for correction of hyperglycaemia.
◦ Change in medications that influence glycaemia – notably steroid
dose reduction.
 Patient factors:
◦ Use of lipohypertrophied insulin injection sites.
◦ Missed meals, NBM status or poorly timed carbohydrate meal/
snacks
◦ Reduced appetite - Pre-mixed insulins are usually inappropriate
when oral intake is reduced significantly or is erratic.
◦ Increasing exercise/ physical activity with physiotherapy.
◦ Intercurrent illness with fluctuation in renal and hepatic function.

16.  A mild case of hypoglycaemia can be treated
through eating or drinking 15-20g of fast acting
carbohydrate such as glucose tablets, sweets,
sugary fizzy drinks or fruit juice.
 Some people with diabetes may also need to take
15-20g of slower acting carbohydrate if the next
meal is not due.
 A blood test should be taken after 15-20
minutes to check whether blood glucose levels
have recovered.
 Severe hypos can be treated with glucagon if a
glucagon injection kit is available and in date.

18. Cambridge University Hospitals NHS Foundation Trust:
“Diabetic ketoacidosis (DKA) management in adults” Version 5; Approved May 2015
“Hypoglycaemia: Patients with diabetes mellitus” Version 3; Approved May 2015
“Ketone testing for adult in-patients with diabetes mellitus guideline” Version 1;
Approved May 2015
Diabetes.co.uk © 2016 Diabetes Digital Media Ltd - the global diabetes community.
Diabetes UK 2016 - Diabetes.org.uk
Diabetes.org - American Diabetes Association.
http://www.nhs.uk/Conditions/Hypoglycaemia/Pages/Symptoms.aspx
http://www.nhs.uk/conditions/Hyperglycaemia/Pages/Introduction.aspx
http://www.nhs.uk/conditions/diabetic-ketoacidosis/Pages/Introduction.aspx
https://www.diabetes.org.uk/Guide-to-diabetes/Complications/Diabetic_Ketoacidosis/
http://www.diabetes.co.uk/diabetes-complications/diabetic-ketoacidosis.html
https://www.diabetes.org.uk/Guide-to-
diabetes/Complications/Hyperosmolar_Hyperglycaemic_State_HHS/