Diabetes occurs when the body either doesn’t produce enough insulin or can’t effectively use the insulin it produces. Insulin is a hormone that helps regulate blood sugar (glucose) levels by allowing glucose to enter cells for energy. When this process is disrupted, blood sugar levels rise, leading to diabetes.

There are two main types of diabetes:
1. Type 1 Diabetes – This is an autoimmune condition where the body’s immune system mistakenly attacks insulin-producing cells in the pancreas, leading to little or no insulin production. The exact cause is unknown, but genetic and environmental factors (like viral infections) may play a role.
2. Type 2 Diabetes – This occurs when the body becomes resistant to insulin or doesn’t produce enough to maintain normal blood sugar levels. It is often linked to genetics, obesity, physical inactivity, and poor diet.

Other forms include gestational diabetes, which occurs during pregnancy, and prediabetes, where blood sugar levels are higher than normal but not high enough for a diabetes diagnosis.

Source: ChatGPT

I would phrase it as insulin signals the cells to open the doors for glucose to enter the cells. Even without insulin the cells can produce energy via fatty acid metabolism. Both glucose and fatty acids are metabolized through the citric acid cycle (a.k.a Krebs cycle). When you get chronic elevated insulin levels (from consuming a high carb diet), your cells become insulin resistant, and eventually you get diabetes.

So even without insulin, your body will be fine as long as you have enough fatty acids for energy.

Diabetes is because your pancreases already lost it function or deteriorate overtime.
causing your pancreases insulin not sensitive (insulin resistance)(prediabetic)... and this make your body glucose cannot absorb by your body cells.
this loop overtime making your body fat, both insulin and glucose are poison making your others organ to inflammation and other type of disease such as kidney deteriorate as well...and if you still do not take care your pancreases
then your pancreases eventually malfunction and lead to diabetes because pancreases cannot produce any insulin anymore.