Can you be thin and still have diabetes? The big myth explained

Diabetes brings one image to mind: a heavier person struggling with high blood sugar. But that image misses a large and important truth. Many people who look slim or who have a normal body weight can also develop diabetes. This isn’t a rare exception; it’s a reality backed by science and clinical experience. In India and South Asia, where genetics and body composition differ from Western populations, doctors have seen this again and again. Here is all you need to know about why thin people can get diabetes, what research says, and what this means for health.For decades, many people assumed that only overweight individuals develop type 2 diabetes. That idea became widespread because obesity is indeed a major risk factor. But it is not the only one. Diabetes develops when the body’s ability to produce or use insulin goes awry. This can happen even when someone has a low or normal body mass index. Evidence shows that in many Asian and Indian populations, a large portion of people diagnosed with type 2 diabetes were not overweight at the time of diagnosis, as per a study published in the NIH. These individuals may appear slim but carry hidden fat deep in the abdomen around organs, a kind of fat that disrupts insulin’s work. This phenomenon shows that weight on the scale is only part of the story.Experts describe a pattern seen in many South Asian people as the “thin-fat” phenotype. In this case, a person has a normal BMI but carries a disproportionate amount of visceral fat around internal organs. This hidden fat triggers inflammation and insulin resistance, increasing diabetes risk even in lean individuals.Some Indians, despite low body weight, suffer from both insulin deficiency and insulin resistance, a mix that pushes blood sugar levels high even in the absence of obvious obesity.Researchers found that many lean or normal-weight adults still had high rates of type 2 diabetes. In Asian Indian men, nearly one in five lean individuals had diabetes compared with much lower rates in similar white populations.Dr Manoj Chawla, Consultant Diabetology at P.D. Hinduja Hospital & MRC, points out that the old belief linking diabetes only with obesity is outdated. “Obesity is a significant risk factor,” he says, “but not the sole cause. People of normal weight or even underweight can develop diabetes.” Many Indians diagnosed with diabetes fall into this group, because factors such as genetics and visceral fat matter as much as, or more than, BMI. In his view, weight alone is a poor marker of metabolic risk.Dr Saptarshi Bhattacharya, Senior Consultant Endocrinology at Indraprastha Apollo Hospitals, notes that this leads to delayed diagnosis. “Lean individuals and physicians often assume the risk is low,” he says. This assumption can push diagnosis to a later stage when symptoms are more severe.The symptoms in lean people, fatigue, thirst, frequent urination, blurred vision, are largely similar to those in heavier patients. However, lean patients may also experience unexplained weight loss or muscle wasting, which can be mistaken for other conditions. They may even have different subtypes of diabetes that present abruptly. These include latent autoimmune diabetes in adults (LADA) and ketosis-prone diabetes, which can confound diagnosis unless tested. There are four core drivers that help explain diabetes in thin people:Slim people may still carry excess fat around the abdomen, fat that disrupts insulin’s action far more than fat stored under the skin. This hidden fat can later promote inflammation and insulin resistance in the body.South Asian populations, including many Indians, tend to develop diabetes at lower BMI levels than Western groups. Genetic studies published in the Panacea Journal of Medical Sciences, show that lean Indians with diabetes often have lower beta-cell function, meaning their pancreas makes less insulin, which increases diabetes risk even without obesity.Diets heavy in refined carbohydrates and low in protein are common in many regions. These foods cause frequent insulin spikes and may encourage visceral fat storage even when overall weight is low.Research suggests that body composition differences begin early in life. South Asians can be born with relatively higher body fat compared with Western infants, which tracks into adulthood and raises metabolic risk independent of BMI.Understanding that diabetes can strike in lean bodies matters for prevention and early detection. Anyone, whether slim, average, or heavy, should be mindful of risk if they have symptoms or family history. Simple tests such as fasting glucose and HbA1c can catch elevated sugar before serious complications arise. Regular screening is especially important in populations at higher risk due to genetics or ethnic profile.Remember: fat distribution and internal metabolic health are more meaningful than the number on the weighing scale.Medical experts consulted This article includes expert inputs shared with TOI Health by:Dr Manoj Chawla, Consultant Diabetologist at P.D. Hinduja Hospital & MRCDr Saptarshi Bhattacharya, Senior Consultant Endocrinology at Indraprastha Apollo HospitalsInputs were used to explain why diabetes is not limited to obesity and why even thin individuals should consult a doctor if they have symptoms or risk factors.