Diabetes occurs when there is too much glucose, a type of sugar, in the blood. If not controlled, high blood glucose levels will eventually lead to damage to many parts of the body.
Blood-sugar levels are normally controlled by a hormone called insulin, which is made in the pancreas. High blood glucose levels may be caused by:
- insulin deficiency – when the pancreas is not able to make enough insulin, or
- insulin resistance – when your body is not responding to insulin as it should.
What is insulin?
Insulin is a natural hormone that helps glucose enter the body's cells where it is used for energy. If there is not enough insulin, or it is not working well to act as a key to open the channel for glucose to enter the cells, glucose builds up in your bloodstream.
- The normal level of glucose in the body is between 4 and 8 mmol/L.
- When you have diabetes, your body is not able to control your blood glucose levels and keep it in the safe range.
- If the blood glucose level is too low, hypoglycaemia (low blood glucose) occurs and you feel sweaty, weak and dizzy, and need to eat some glucose right away.
- If the blood glucose level is too high, hyperglycaemia (high blood glucose) can occur.
- Symptoms depend on how high or rapidly the level changes but can include excess thirst, passing excess urine, blurred vision etc.
What are the common types of diabetes?
There are three main types of diabetes and one type of prediabetes.
Type 1 diabetes – this is caused by insulin deficiency. It often starts in childhood and can appear with little warning. Approximately 10% of people with diabetes have type 1 diabetes. Read more about
Read more about type 1 diabetes, including causes, symptoms, diagnosis, treatment and self-care.
Type 2 diabetes – is the most common type of diabetes affecting about 90% of all people with diabetes. With type 2 diabetes, the main problem is insulin resistance, although insulin deficiency can also develop. Approximately 90% of people with diabetes have type 2 diabetes.
Read more about type 2 diabetes, including causes, symptoms, diagnosis, treatment, prevention and self-care.
Diabetes in pregnancy – this is when you get diabetes during pregnancy. It is also called gestational diabetes. It needs to be managed carefully to improve the health of mum and baby. It usually goes away after having the baby but can progress to type 2 diabetes so regular check-ups are recommended.
Read more about gestational diabetes, including causes, symptoms, diagnosis, treatment, prevention and self-care.
Pre-diabetes – this is when your blood glucose (sugar) level is higher than normal, but not high enough to be diagnosed as type 2 diabetes yet. As the rates of obesity and being overweight have increased, so have the rates of prediabetes and insulin resistance. It now affects about 1 in 4 New Zealanders aged 15 or over.
Read more about pre-diabetes, including causes, symptoms, diagnosis, treatment, prevention and self-care.
Information for health professionals
The information on this page will be of most interest to clinicians (doctors, nurses, specialists, etc) and those interested in more detail.
- Clinical guidelines
- Regional HealthPathways NZ
- Continuing professional development
Management of type 2 diabetes NZ Primary Care Handbook, pages 45-64, including:
- Glycaemic control
- Management of blood pressure
- Preventing complications
- Starting insulin
Understanding the role of insulin in the management of type 1 diabetes BPAC NZ, 2019
Slowing progression of renal dysfunction in patients with diabetes BPAC NZ, 2019
Optimising pharmacological management of HbA1c levels in patients with type 2 diabetes: from metformin to insulin BPAC NZ, 2019
A rising tide of type 2 diabetes in younger people: what can primary care do? BPAC NZ, 2018
Managing patients with type 2 diabetes: from lifestyle to insulin BPAC NZ, 2015
Improving glycaemic control in people with type 2 diabetes BPAC NZ, 2013
The new role of HbA1c in diagnosing type 2 diabetes BPAC NZ, 2012
Regional HealthPathways NZ
Access to the following regional pathways is localised for each region and access is limited to health providers. If you do not know the login details, contact your DHB or PHO for more information:
Continuing professional development
The DAWN2 Study: Putting the Results into Your Practice (Jan 2015)
Webinar by the National Diabetes Education Program with Mark Peyrot, PhD, principal investigator for the DAWN2 study and Martha M. Funnell, MS, RN, CDE, FAADE, member of the DAWN2 Study Group.
Summarises key findings from the DAWN2 study and describes findings and practical strategies that health care teams can use to address psychosocial issues with their patients. January 2015.
The DAWN2 Study: Video (mp4 Format, 272MB) USA
The DAWN2 Study: Transcript (docx Format) USA
The DAWN2 Study: Slides (PDF Format) USA
The Insulin Toolbox: Understanding the Options (Sept 2014)
Insulin therapy helps people with diabetes control blood glucose levels.
During this webinar, Dr. Francine Kaufman, Distinguished Professor Emerita of Pediatrics and Communications at The University of Southern California and Chief Medical Officer and VP of Global Clinical, Medical & Health Affairs for Medtronic, explains the different types of insulin and methods of insulin delivery.
Dr. Kaufman also presents case studies to help health care professionals understand the factors influencing insulin therapy decisions.
In addition, Joanne Gallivan, M.S., R.D., Director of the NDEP at the National Institutes of Health shares related resources available from the NDEP, the National Diabetes Information Clearinghouse, and partner organisations.
This webinar was held in September 2014.
The Insulin Toolbox: Video (Youtube, 60 minutes) USA
The Insulin Toolbox: Transcript (PDF Format) USA
The Insulin Toolbox: Slides (PDF Format) USA
Using Shared Decision-Making to Empower Underserved Populations with Diabetes (March 2015)
Shared decision-making is a collaborative process that allows the patient and provider to make health care decisions together. Studies have shown that including patients in treatment decisions and building patient trust in providers can improve health outcomes.
During this webinar, Dr. Monica Peek, Assistant Professor in the Division of General Internal Medicine at the University of Chicago and Dr. Linda Siminerio, Professor of Medicine in the Division of Endocrinology and Metabolism at the University of Pittsburgh explore the importance of shared decision-making and patient-provider communication for reaching underserved populations with diabetes.
Dr. Siminerio introduces science supporting patient communication and shared decision-making, while Dr. Peek describes social and cultural barriers to shared decision-making for vulnerable populations. This webinar was held in March 2015."
Link to video and presentation
PHARMAC seminar series
The Goodfellow Unit podcast
Diabetes Diagnosis – Tim Kenealy Goodfellow Unit, 2017
"Dr Timothy Kenealy talks about diagnosing diabetes in primary care. Tim was a GP in South Auckland for 25 years and is an associate professor of integrated care at the University of Auckland. One of his main research interests is in diabetes in primary care."