Over the long term, hyperglycemia can cause complications.
Hyperglycemia is defined as blood glucose (sugar) levels that are higher than the target values for the majority of people with diabetes:
- above 7 mmol/L, fasting or before a meal
- above 10 mmol/L, two hours after the begining of a meal
Hyperglycemia occurs when the amount of insulin in the blood is insufficient or ineffective. When glucose circulating in the blood cannot enter the cells because of a lack of insulin, it accumulates in the blood and raises a person’s glycemia (blood glucose levels) .
Some people may not notice their hyperglycemia. However, above a certain threshold, high blood sugar can lead to the following symptoms:
- increased urination
- intense thirst
- excessive hunger
- involuntary weight loss
The primary causes of hyperglycemia are:
- a diet abnormally high in carbohydrates
- reduced physical activity
- insufficient insulin and/or antidiabetic medication (dosage error or a skipped dose)
- physical stress (illness, surgery, infection, etc.) or psychological stress (mourning a death, new job, moving, etc.)
- taking certain drugs (e.g.: cortisone)
Hyperglycemia can also be caused by two lesser known phenomena: the dawn phenomenon and the Somogyi effect.
In most cases, hyperglycemia can be avoided by taking the following precautions:
- Measure your blood glucose (sugar) levels regularly.
- Follow a daily meal plan designed by a dietitian.
- Take your insulin or antidiabetic medication as prescribed.
- Adjust your insulin dose based on your medical prescription
If you experience hyperglycemic symptoms, you should:
- take your blood glucose (sugar) readings frequently
- if you have type 1 diabetes: if your blood glucose level is higher than 14 mmol/L, check for ketones in your urine or blood
- drink water regularly to prevent dehydration
- adjust your insulin as medically prescribed
- identify the cause of the hyperglycemia and take appropriate measures, if possible
Call a doctor or get to Emergency if:
- your blood glucose reading is higher than 14 mmol/L with ketones
- in your urine: a “medium” to “high” level
- in your blood: a level higher than 1.5 mmol/L
- if you have type 1 diabetes: your blood glucose level is higher than 20 mmol/L with nausea, vomiting and/or abdominal pain
- if you have type 2 diabetes: your blood glucose level is higher than 25 mmol/L with excessive drowsiness
- you cannot retain liquids due to vomiting or diarrhea
- your state of consciousness changes: confusion, agitation, lack of reaction to stimulation, hallucinations or unusual behaviour
- you exhibit signs of dehydration: dry mouth, sunken eyes, dry skin, etc.
- your body temperature has stayed above 38.5 °C for more than 48 hours.
These symptoms could signal a hyperglycemic emergency.
Research and text: Diabetes Québec Team of Health Care Professionals
June 2014 (updated on August 2018)
©All rights reserved Diabetes Quebec
S.A. Imran et al. Diabetes Canada 2018 Clinical Practice Guidelines for the Prevention and Management of Diabetes in Canada: Targets for Glycemic Control. Can J Diabetes 2018; 42 (Suppl 1): S42-S46.
Geoffroy L., and Gonthier, M., (2012) “L’hyperglycemia et l’acidose diabétique,” Le diabète chez l’enfant et l’adolescent, 2nd edition,. Montréal: Éditions du CHU Ste-Justine, pp. 355-364.