Diabetes: How Blood Sugar Works and What Goes Wrong

A word like diabetes can sound frightening and complicated, but at its heart it's about one thing: how your body turns food into energy, and what happens when one hormone stops doing its job. Whether you've just been diagnosed, been told you're at risk, or are trying to understand a family member's condition, this guide explains what diabetes actually is, the differences between the types, why steady control matters, and — honestly — where regenerative medicine does and doesn't fit.

What is diabetes?

Diabetes is a condition in which the body can't properly regulate the level of sugar — glucose — in the blood ¹. Glucose is your main fuel, and a hormone called insulin is the key that lets it move out of the bloodstream and into your cells to be used for energy. In diabetes, either there isn't enough insulin, the body doesn't respond to it properly, or both — so glucose stays in the blood instead of powering your cells ¹.

It is now one of the most common chronic conditions in the world. The World Health Organization estimates that around 830 million people were living with diabetes in 2022 — up from 200 million in 1990 — and more than 95% of them have type 2 diabetes ². Left unmanaged, persistently high blood glucose gradually damages blood vessels and nerves, which is why diabetes is taken seriously even when it causes few symptoms at first.

How your body manages blood sugar

Blood-sugar control is a team effort. The pancreas releases insulin when glucose rises after a meal; the liver stores glucose and releases it when you need it; and your muscles and tissues take glucose in and burn it for energy ¹. When this system is working, your blood sugar stays in a healthy range without you ever noticing. Diabetes is what happens when one part of that loop breaks down — and the two main types break it in different places.

The main types of diabetes

Type 1 diabetes is an autoimmune disease: the immune system mistakenly destroys the insulin-producing cells in the pancreas, so the body makes little or no insulin ¹. It often appears in childhood or early adulthood, comes on relatively quickly, and means lifelong insulin treatment. It is not caused by diet or lifestyle.

Type 2 diabetes is by far the most common form — more than 95% of cases — and develops gradually ². Here the problem is mainly insulin resistance: the body still makes insulin, but cells stop responding to it well, and over time the pancreas can't keep up. It's strongly linked to weight, inactivity, and genetics, and the WHO notes type 2 is often preventable ².

Gestational diabetes develops during pregnancy and usually resolves after delivery, though it needs monitoring to protect mother and baby and signals a higher future risk of type 2 ¹.

Symptoms to be aware of

Diabetes symptoms can be subtle, especially in type 2, which is why many people have it for years before diagnosis. Common signs include ³:

• Increased thirst and frequent urination
• Persistent tiredness or low energy
• Blurred vision
• Slow-healing cuts or wounds
• Increased hunger and, sometimes, unexplained weight change

Because the early signs are easy to dismiss, screening matters for anyone with a family history or other risk factors.

Why steady control matters

The reason doctors push for good blood-sugar control is what happens over the long term. Persistently high glucose damages blood vessels and nerves throughout the body, and the WHO links diabetes to serious complications: heart attacks and stroke, kidney failure, vision loss, nerve damage, and lower-limb problems that can lead to amputation ². Nerve damage in particular — diabetic peripheral neuropathy — is one of the most common complications, which is why foot care and regular checks are part of routine diabetes management.

None of this is meant to frighten. The point is the opposite: these complications are largely driven by uncontrolled blood sugar, and good management dramatically lowers the risk.

How diabetes is managed

Diabetes care has improved enormously, and most people manage it well with a combination of approaches tailored to the type and the person ¹³:

• Lifestyle foundations — balanced nutrition, regular physical activity, and weight management are central, especially for type 2, where they can substantially improve blood sugar.
• Monitoring — checking blood glucose (and longer-term markers like HbA1c) to keep levels in a healthy range.
• Medication — for type 1, insulin is essential and lifelong. For type 2, there's now a broad toolkit, from metformin to newer classes of medicine that improve blood sugar and also protect the heart and kidneys. Among the newest are the GLP-1 "weight-loss peptides" such as semaglutide, which began life as diabetes drugs.
• Coordinated care — regular reviews and screening of the eyes, kidneys, and feet to catch complications early.

The aim is steady, individualized control — not perfection — sustained over the long term.

Where does regenerative medicine fit?

This is the part that needs the most honesty, because "stem cells for diabetes" is one of the most over-marketed claims out there. The genuine, exciting research is cell replacement for type 1 diabetes — and it is a very specific thing. Because type 1 destroys the insulin-making beta cells, replacing those cells can restore insulin production. In June 2023 the FDA approved the first cellular therapy for type 1, donislecel (Lantidra) — transplanted donor islet cells — with about two-thirds of recipients insulin-independent at one year; and stem-cell-derived islet cells (such as the investigational VX-880) are showing real promise in early clinical trials ⁴.

But the honest caveats are big. This approach is for type 1 only, it's largely experimental or limited to a narrow group, it generally requires lifelong immune-suppressing drugs, and it's delivered in specialist transplant programmes — not as a walk-in infusion ⁴. Crucially, this islet-replacement research is not the same as the mesenchymal "stem cell therapy" some clinics sell as a diabetes treatment. (For why that distinction matters — what those cells actually do — see what stem cells can really do.) And for type 2 diabetes, there is no established stem-cell therapy at all. Anyone offering a stem-cell "cure" for diabetes deserves real scepticism.

What we see at the clinic

When people ask us whether stem cells can cure their diabetes, we give them the straight version: the proven foundation is the conventional care that controls blood sugar and prevents complications, and the genuine cell-replacement science is a specialist, type-1 research field — not something to swap your insulin or medication for. We'd far rather someone leave a consultation with an accurate picture and realistic expectations than with false hope. Honest information is the most useful thing we can offer on this topic.

Common questions

Can type 2 diabetes be reversed? Many people can bring type 2 into remission — normal blood sugar without medication — particularly through significant weight loss and lifestyle change earlier in the disease. "Remission" isn't quite the same as "cured," and it needs maintaining, but it's a realistic goal worth discussing with your doctor.

Can stem cells cure diabetes? Not as an off-the-shelf treatment. Cell-replacement therapy for type 1 is advancing in specialist settings and early trials, but it's experimental, usually needs immunosuppression, and isn't a routine cure ⁴. For type 2, there's no established stem-cell treatment — be wary of clinics claiming otherwise.

Is type 1 caused by eating too much sugar? No. Type 1 is an autoimmune condition and is not caused by diet or lifestyle ¹. That myth is both wrong and unfair to people living with it.

What is prediabetes? Prediabetes means blood sugar is higher than normal but not yet in the diabetes range. It's an important warning sign — and often a reversible one, with lifestyle changes that lower the risk of progressing to type 2.

Does diabetes always need insulin? Type 1 always requires insulin. Type 2 often doesn't, at least at first — it's frequently managed with lifestyle and non-insulin medicines, though some people do need insulin later ³.

Key takeaway

Diabetes is a disorder of insulin and blood-sugar control — type 1 from an autoimmune loss of insulin, type 2 (the great majority) from insulin resistance. It's common and serious, but highly manageable, and good control is what prevents long-term complications. Cell-replacement research is a genuine frontier for type 1, yet it remains specialist and experimental — and quite distinct from the "stem cell" claims marketed for diabetes, which don't hold up. The proven path runs through steady, individualized medical care.