The big picture

Type 2 diabetes is a long-term condition characterised by insulin resistance—where the body’s cells do not respond properly to insulin—and, over time, reduced insulin production.

How glucose and insulin work normally

Your body consists of trillions of tiny cells, like a bustling city filled with millions of houses. Just as your home needs electricity to power the fridge, TV, and lights, your cells rely on glucose from food as their energy source.

When you eat carbohydrates—fruit, vegetables, whole grains, pasta, or bread—your body breaks them down into glucose, which travels through the bloodstream to reach your cells.

Picture glucose as big, bouncy energy balls zooming down the freeway toward the houses. To enter the cells (houses), glucose needs a key—insulin, produced by the pancreas.

In someone without insulin resistance, the key fits perfectly. The door opens, glucose enters, and your body gets the energy it needs.

What causes insulin resistance?

Insulin resistance develops when cells become less responsive to insulin. Factors include overall body fat, fat stored inside the liver and muscles, low physical activity, genetics, and regularly taking in more energy than the body needs.

Imagine a door lock jammed with chewing gum. The key doesn’t work properly—the door won’t open. In the body, the gum is extra fat and related substances in liver and muscle cells that interfere with insulin’s message. Even though insulin (the key) is present, it cannot effectively unlock the cell, so glucose remains in the bloodstream.

The pancreas senses rising blood glucose and produces more insulin (more keys) to overcome the resistance. For a while, this helps, but extra keys cannot fully fix a gummed-up lock. Over time, insulin-producing cells gradually lose their ability to make enough insulin. By the time type 2 diabetes is diagnosed, much of the pancreas’s insulin-making capacity may already be reduced.

The consequences

When cell doors aren’t opening properly, glucose builds up in the bloodstream. Cells aren’t getting the energy they need, which can make people feel tired. Using the city analogy, energy balls are stuck outside the houses instead of powering everyday activities.

Over time, high blood glucose can damage blood vessels, organs, and tissues. Fortunately, the body can respond positively to changes in lifestyle and diet, giving cells a chance to regain responsiveness.

The solution

The good news is that insulin resistance can often be improved. Eating patterns and lifestyle changes that reduce fat inside the liver and muscles help cells respond better to insulin.

For many people, eating mostly vegetables, fruits, beans, and whole grains in a low-fat, plant-based pattern can improve insulin resistance, support weight loss, reduce harmful fat stores, and improve blood glucose control. In some people with type 2 diabetes, intensive and sustained lifestyle changes can lead to very good blood glucose control and, in some cases, even remission.

Returning to the analogy: If excess fat is gumming up the lock, reducing the extra fat gives your body a chance to gradually clear the gum. As insulin works better, the key fits more effectively, doors open more easily, and glucose can enter the cells.

In many individuals, this leads to substantial improvement in blood glucose levels and, under medical supervision, may allow reduction of certain medications.

Type 1 diabetes and insulin resistance

People with type 1 diabetes can also develop insulin resistance, sometimes called ‘double diabetes’ (type 1 diabetes plus insulin resistance). Here, resistance is often linked to excess body fat, fat in the liver and muscles, higher insulin doses, and features of metabolic syndrome.

While type 1 diabetes itself cannot be reversed, insulin resistance can often be improved through lifestyle changes and risk-factor management. This may reduce insulin requirements and help smooth out blood glucose levels.