High Blood Sugar : What really happens inside your body when sugar stays high

timesofindia.indiatimes.com · Feb 20, 2026 · Collected from GDELT

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Elevated blood sugar levels can quietly wreak havoc on the body, gradually injuring cells and organs long before diabetes is identified. This initial phase is characterized by inflammation and insulin resistance, posing a risk even to those who appear slim. Critical organs, such as blood vessels and nerves, bear the brunt, raising the likelihood of heart disease and various complications.High blood sugar does not always shout. Most of the time, it whispers. It works quietly inside the body, changing cells, tiring organs, and setting the stage for disease long before diabetes is diagnosed. Many people feel “mostly fine,” yet damage is already unfolding. Doctors say this silent phase is where the real story lies. Understanding what happens inside the body during this stage can help prevent years of avoidable harm.The first silent injury no one feelsWhen blood sugar stays high for weeks or months, the earliest damage happens at the cell level. Excess glucose begins to stick to proteins and fats in the body. This process forms harmful compounds known as advanced glycation end products, or AGEs. These compounds stress cells and trigger inflammation.Dr Sahil Kapoor, Senior Consultant - Family Medicine & Wellness Expert at Aakash Healthcare, explains, “The first damage is usually inflammation and stress in the cells. Excess glucose sticks to proteins and fats and makes compounds that damage cells. Blood vessels and nerves are particularly sensitive.” How to reduce your sugar intake without feeling deprived: 9 foods for managing diabetes There are no obvious symptoms at this stage. Yet insulin resistance starts building quietly. Nerves get irritated. Blood vessels weaken. By the time discomfort appears, the damage has already progressed.Why thin bodies are not protectedHigh sugar does not care about appearance. A person can look thin, active, and outwardly healthy while internal damage continues. Doctors often see insulin resistance in people with normal weight, especially when fat collects around organs like the liver and pancreas.Dr Kapoor notes, “Body size does not reflect what is happening inside. A thin person can still have fat around the organs, insulin resistance, or genetic risk.”Muscles and the liver may fail to process glucose properly. Hormones fall out of balance. Metabolic health depends on how the body uses energy, not on clothing size or body shape. Early changes can often be reversed with better food choices, physical activity, and weight management. How insulin slowly loses its powerInsulin is the hormone that helps sugar enter cells for energy. When sugar remains high, insulin is released again and again. Over time, cells stop responding. The signal becomes background noise.Dr Kapoor describes it clearly: “The cells start to ignore the insulin signal like turning off a constant noise. That is insulin resistance.”The pancreas works harder to keep up. It produces more insulin to force sugar into cells. Eventually, it gets exhausted. Sugar levels rise further, even though insulin is still present. This vicious cycle is central to type 2 diabetes.Large studies, including the one publihsed in MDPI, show that insulin resistance begins years before diabetes is diagnosed, often without symptoms.Organs that suffer first and quietlyCertain organs are especially vulnerable to high sugar. Blood vessels are the earliest targets. Tiny vessels narrow and weaken, reducing oxygen supply. Nerves lose their ability to send clear signals. Kidneys struggle to filter waste. The retina at the back of the eye becomes fragile.These changes are slow and painless. That is what makes them dangerous. According to long-term data from the UK Prospective Diabetes Study (UKPDS), early vessel damage strongly predicts later complications, even when sugar levels are only moderately high.Doctors stress that once organ function declines, recovery becomes harder. Early control matters more than many realise.Sugar, blood vessels, and the heartHigh sugar injures the inner lining of blood vessels, called the endothelium. This lining helps vessels relax and contract smoothly. Sugar makes it stiff and inflamed. Cholesterol sticks more easily and forms plaques. Blood becomes thicker and more likely to clot.Dr Kapoor explains, “High sugar hurts the lining of the blood vessels and makes them stiff and inflamed. Over time, arteries harden, cutting blood flow to the heart and brain.”This is why high sugar raises the risk of heart attacks and strokes, even in people without diagnosed diabetes. Research in The Lancet Diabetes & Endocrinology shows that cardiovascular risk increases steadily with rising blood sugar, not only after crossing diabetic thresholds.Fatigue, immunity, and the hidden daily costMany people believe high sugar only matters once diabetes appears. Clinically, doctors see effects much earlier.Dr Ajay Kumar Gupta, Senior Director & Head - Internal Medicine at Max Super Speciality Hospital, Vaishali, says, “Persistent tiredness, brain fog, and low energy are some of the most frequent but often misinterpreted issues people experience when they have high sugar levels over a long period.”The body is full of sugar, yet cells cannot use it efficiently. Energy stays locked out. Mood swings and mental fatigue follow. High sugar also weakens immune cells. Wounds heal slowly. Infections become more common.Dr Gupta adds, “High glucose levels make it harder for white blood cells to work properly and reduce oxygen and nutrient supply to tissues.”The good news is timing matters. Early changes can often be reversed with better food choices, physical activity, and weight management. Long-term exposure, however, can cause permanent nerve, eye, kidney, and vessel damage.Medically consulted byThis article includes expert inputs shared with TOI Health by:Dr Sahil Kapoor, Senior Consultant - Family Medicine & Wellness Expert at Aakash HealthcareDr Ajay Kumar Gupta, Senior Director & Head - Internal Medicine at Max Super Speciality Hospital, VaishaliInputs were used to explain what happens inside the body when blood sugar remains high and why timely medical consultation is essential, regardless of body weight.