Understanding Diabetes


Diabetes (or diabetes mellitus) is not one disease but a group of endocrine (hormonal) diseases. Commonly, we separate these out into type 1 diabetes, type 2 diabetes and gestational diabetes, which occurs in pregnancy. However, there are grey areas of diagnosis and other forms of diabetes including MODY (Maturity-onset diabetes of the young) and LADA (latent autoimmune diabetes of adults).

The different types
Type 1 diabetes is an autoimmune condition with a strong genetic component. It occurs spontaneously (although there appears to be some triggers), often diagnosed in younger ages and requires life-long administration of insulin injections. The reason for this is that the immune system attacks the beta cells in the pancreas, destroying them and their ability to produce the hormone insulin. Insulin is required for the digestion of food (primarily carbs) and it unlocks transporters into cells to allow glucose (sugar) to move from the blood stream into our cells to be used for energy.

Type 2 diabetes occurs more slowly over time. It starts out when the hormone insulin is produced in either adequate or excess amounts but the body is “resistant” to its function. It may progress to the point where the beta cells of the pancreas “burn out” from producing so much insulin that they are no longer able to produce enough or any insulin.

At this point, an insulin shot may be required. Type 2 diabetes often occurs in conjunction with other conditions, including non-alcoholic fatty liver disease, hyperlipidemia, hypertension and obesity—collectively known as the metabolic syndrome.

It occurs commonly in older adults, although rates among children and young adults are increasing. It is strongly linked with lifestyle and genetics, occurring more commonly in certain ethnicities.

Gestational diabetes occurs in pregnancy and is a result of insulin resistance as a result of the action of opposing placental hormones. It is also linked with older age coming into pregnancy, elevated bodyweight and ethnicity. If blood glucose levels are unmonitored and uncontrolled, gestational diabetes poses severe risks to mum and baby such as macrosomia, neonatal hypoglycaemia and stillbirth.


Diagnosis and monitoring
Type 1 diabetes commonly presents abruptly and severely. Often a person will become unwell with Diabetic Ketoacidosis (DKA) following symptoms of increased thirst, increased urination, lethargy and unexplained weight loss. This is due to a sudden elimination of insulin—meaning glucose remains in the blood stream, unable to be digested. The body breaks down muscle and fat tissue for fuel in the form of ketone bodies. These accumulate in the blood stream, creating an acidotic environment.

Type 2 diabetes presents slowly over time and may be picked up incidentally through surveillance. In both, “HbA1c” (how much glucose is attached to our red blood cells) is the measurement used with repeat measure ≥50mmol/mol indicating a diagnosis. As these cells have an approximate lifespan of three months, this reflects an average of blood glucose levels over the past three months. Gestational diabetes is diagnosed by an oral glucose tolerance test (OGTT) where the pregnant person drinks 75g of sugar and blood glucose is measured at fasting and at two hours. If one of these values is elevated, this constitutes a diagnosis.

There are no known prevention strategies for type 1 diabetes. We cannot change our genetics or who our parents are. A trigger to the immune system (such as a virus) can trigger type 1 diabetes in individuals genetically susceptible, although this may not always be the case.

Like type 1 diabetes, there is a genetic component of type 2 diabetes we cannot control. However, there is a much larger lifestyle component we can control, so there is hope. Increased body weight and physical inactivity are major risk factors.2 Reducing bodyweight can help reduce excess fat stored around organs and muscle tissue, allowing insulin to work better. Exercise also allows excess glucose to be used directly by the muscles and increases sensitivity to insulin.


Treatment and management
Diabetes management options have come in leaps and bounds. Last year marked 100 years since the discovery of insulin as a miracle treatment option. With the advent of insulin, type 1 diabetes became a chronic health condition rather than a death sentence. Indeed, insulin profiles and delivery methods have become so advanced that using a continuous glucose monitoring (CGM) sensor combined with an insulin pump almost mimics the function of a pancreas, allowing greater freedom in daily activities, food choices and sports. A CGM is a small device with a filament inserted into the skin, usually applied to the tricep, which continuously measures glucose levels and transmits this to a reader or an app on a phone or an insulin pump giving 24-hour real time data. An insulin pump is another device which continuously delivers insulin. By communicating via Bluetooth, insulin can be stopped if a low blood glucose is predicted or more can be delivered if high glucose is detected. These fine adjustments allow for much improved diabetes control as they are able to react to day-to-day variations.*

In type 2 diabetes, lifestyle continues as the foundation of treatment with 5–10 per cent bodyweight reduction markedly improving glycemic control.2 Healthy eating and physical activity, the vehicle to weight loss, also reduce the risk of type 2 diabetes on their own. In cases where pharmaceutical therapy is required, we have available a range of oral medications that can do anything from helping your insulin work better to increasing insulin production of the beta cells to blocking the re-absorption of glucose in the kidneys, lowering blood sugar levels.

Practically speaking, some general nutrition guidelines to start with include: eating regular balanced meals including some starchy carbohydrates, some protein and plenty of non-starchy vegetables and choosing low-sugar, low-saturated fat, low-salt, and high-fibre food, drinking plenty of water, and avoiding sweetened drinks and foods.1 Being physically active can mean aiming for a cumulative 150 or more minutes per week of moderate-to-vigorous aerobic activity such as a brisk walking, cycling, running or swimming as well as avoiding long stretches of inactivity. It’s always a good idea to get up and move around every 30 minutes.2 These recommendations are also similar if you’re trying to prevent diabetes. Of course, none of these can replace personalised guidance from a healthcare professional.

Prevention or effective treatment are key, as the complications of both types of diabetes are the same. Chronic excess glucose damages major and minor blood vessels causing kidney, nerve, eye, cardiovascular complications and delayed healing.


Future steps
The future of diabetes is both concerning and encouraging. The prevalence of diabetes in New Zealand has increased over the past 10 years and is predicted to continue to increase with current prevalence of five per cent of the population having type 2 diabetes.3 The trajectory is similar in Australia with a plateau between 2016 and 2020 (this primarily represents type 2 diabetes as around 10 per cent of diabetes cases are type 1).4 While research, policy, healthcare and education are needed to help reduce these rates, we have many tools to address this disease. We have the capacity to make choices for our health even when the current obesogenic environment may not be ideal. We can apply lifestyle change and utilise treatment options to allow for good blood glucose control, reducing risk of long-term complications and giving us the opportunity to live a long and healthy life.

Dr Kiri Newsome works as a diabetes specialist dietitian across Taranaki, New Zealand, where she lives with her husband Richard.

For more information see: Diabetes New Zealand, Diabetes Australia,The New Zealand Society for the study of Diabetes, or Australian Diabetes Society

*CGM and insulin pumps may not be fully funded in New Zealand and Australia and are subject to criteria being met.

  1. Zhang, C, Rawal, S & Chong, YS, “Risk factors for gestational diabetes: is prevention possible?” Diabetologia (2016) 59:1385–1390.
  2. The Diabetes and Nutrition Study Group (DNSG) of the European Association for the Study of Diabetes (EASD). “Evidence-based European recommendations for the dietary management of diabetes.” Diabetologia (2023)
  3. Palacios OM, Kramer M, Maki KC. “Diet and prevention of type 2 diabetes mellitus: beyond weight loss and exercise.” Expert Review in Endocrinology and Metabolism (2019) 14(1):1-12.
  4. Ronald J Sigal, Glen P Kenny, David H Wasserman, Carmen Castaneda-Sceppa, Russell D White, “Physical Activity/Exercise and Type 2 Diabetes: A consensus statement from the American Diabetes Association.” Diabetes Care (2006) 29(6):1433–1438.
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