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A fasting glucose between 100 and 125 mg/dL, or an HbA1c between 5.7% and 6.4%, is prediabetes. It usually turns up on a routine office health check, with a fasting sugar of around 110 marked H, in someone who feels completely well. Underneath, muscle and liver have started to resist insulin and the pancreas is working harder to keep sugar in range. About one Indian adult in seven is in this band, according to the national ICMR-INDIAB survey.
In the Chennai prevention trial, 39.3% of the lifestyle group had diabetes after three years, against 55.0% of the control group. In a larger American trial, aiming for a 7% drop in body weight cut new diabetes by 58%. For a 78 kg adult, 7% is about 5.5 kg.
Prediabetes is common in India, and it does not make diabetes certain
Prediabetes is the stretch between normal sugar and type 2 diabetes. The body still clears sugar after a meal, but it needs more insulin to do it, and the fasting number drifts from the 80s and low 90s into the 100s. Some labs print it as impaired fasting glucose when the fasting number is high, or impaired glucose tolerance when the two-hour number is.
The ICMR-INDIAB survey drew blood from 113,043 adults in every state and union territory (Anjana) and found prediabetes in 15.3%, about one adult in seven. Diabetes itself was at 11.4%. Unlike diabetes, prediabetes was about as frequent in villages as in cities, so this is not only a metro problem.
What happens next varies a lot. A review in The Lancet (Tabák) found that each year between one in twenty and one in ten adults with prediabetes move on to diabetes, and roughly as many slip back to normal. Age and family history play a part, and so do the waist, the daily step count and the weight carried over the following years. The same review links prediabetes with early changes in the kidneys, nerves and eyes, which is reason enough to act on a borderline report.
What blood sugar range counts as prediabetes?
Three tests can show it. The American Diabetes Association counts a fasting plasma glucose of 100–125 mg/dL as prediabetes. An HbA1c of 5.7–6.4% counts too, and so does a reading of 140–199 mg/dL two hours after a 75 g glucose drink.
Above those bands is the diabetes range: a fasting sugar of 126 or more, an HbA1c of 6.5% or more, or a two-hour value of 200 or more. Below them is normal.
Indian labs do not all print the same limits. The World Health Organization starts the fasting band at 110 rather than 100, and the ICMR-INDIAB survey used the WHO cut-offs. A fasting reading of 104 may be flagged by one lab and pass quietly at another, so read the number rather than the flag.
An office report with a fasting sugar of 108 and an HbA1c of 5.9% sits in the prediabetes band on both counts, and neither is diabetes. A doctor would usually repeat the test, or confirm it with a second kind, before putting a label on it.
Check it yourself in 2 minutes: three lines on your report, and one look in the mirror
Find the fasting glucose, the HbA1c and, if it was done, the two-hour glucose on your last report, and write each one beside the bands above. One number in the band is a borderline report. Two in the band, or one near the top at 6.2–6.4%, is worth a doctor's visit within a few weeks.
Then check how the sample was taken. A fasting sugar needs eight hours with only water, so late-night chai and biscuits can push it up. A finger-prick glucometer is handy for tracking at home but cannot diagnose prediabetes. HbA1c has blind spots of its own: the American guidance notes that anaemia, recent blood loss or transfusion, kidney disease and some inherited haemoglobin variants can push it too high or too low.
Now the risk factors that make a test worth repeating even if you feel fine. The same guidance lists a parent or sibling with diabetes, blood pressure of 130/80 or more, PCOS, low HDL or high triglycerides, a desk-bound day and diabetes during a past pregnancy. It advises testing every adult from age 35, sooner if overweight with one more risk factor, and for Asian Indians the Indian consensus (Misra) puts overweight at a BMI of 23.
Last, look at the back of your neck and your armpits. Dark, thick, velvety skin there, called acanthosis nigricans, often travels with insulin resistance. Some signs point past prediabetes: getting up two or three times a night to pass urine, a thirst water does not settle, blurred vision or weight falling without trying. Those need a fasting sugar and HbA1c within days.
Why does prediabetes happen, even in slim Indians?
Two things go wrong together. Muscle, liver and fat cells begin to respond less to insulin, which is called insulin resistance, and the pancreas makes extra insulin to keep up until, over years, its beta cells start to tire. The Lancet review notes that both changes begin before sugar readings rise.
Extra fat around the waist is the biggest everyday driver. Fat packed deep in the belly and inside the liver makes insulin work less well. Long hours of sitting, refined grains and sweet drinks add to it. Family history and age add risk you cannot change, which makes the rest more worth working on.
Indians tend to get there at a lower weight. The Indian Diabetes Prevention Programme in Chennai (Ramachandran) noted that its volunteers were younger, leaner and more insulin resistant than people in Western trials, with an average BMI just under 26.
That is why the Indian consensus treats a BMI of 23 as overweight and sets the waist limit at 90 cm for men and 80 cm for women. A man with a modest BMI and a firm, round belly can carry more risk than his weight suggests.
Can prediabetes go back to normal?
For many adults it can, and lifestyle change is the first step doctors recommend. In the US Diabetes Prevention Program (Knowler), 3,234 adults with raised sugar were assigned to an intensive lifestyle programme or a comparison group. The goals were a 7% weight loss and at least 150 minutes of activity a week, and over about three years the lifestyle group developed diabetes 58% less often.
The Indian trial is closer to home. The Chennai team gave 531 adults advice on food and walking, with regular follow-up. Three years later 39.3% of the lifestyle group had diabetes, compared with 55.0% of the control group, a relative cut of 28.5%.
A follow-up of the American volunteers (Perreault) looked at who stayed clear. Those whose sugar had returned to normal at least once during the trial had a 56% lower risk of diabetes in later years than those who stayed borderline.
The trials mostly counted how many avoided diabetes, which is different from everyone returning to normal. Sugar that has settled can drift up again if the weight comes back, so the yearly test stays on the calendar. Some adults at higher risk need more than lifestyle change, which is a call for a doctor who has seen the full report.
Each kilogram lost lowered diabetes risk by 16% in the American trial
Weight was the strongest lever in the Diabetes Prevention Program. Going back through the lifestyle group (Hamman), each kilogram lost went with a 16% lower risk of diabetes, even after allowing for diet and exercise. Those who missed the weight goal but kept up the walking still had 44% fewer new cases.
Muscle is the part to protect, because it soaks up most of the sugar from a meal. In 13,644 American adults (Srikanthan), every 10% rise in muscle relative to body weight came with 12% lower odds of prediabetes. A crash diet of tea and two rotis a day costs muscle along with fat, leaving you lighter but with less of the tissue that clears sugar.
That is why a doctor-led plan starts with a home blood test and a doctor's review. For someone carrying more weight around the middle, it can aim for losing up to 20% of body weight while keeping muscle across many months. The calorie gap stays steady, protein goes into every meal and strength work runs two or three times a week. At a BMI under 23, the waist, muscle and activity matter more than the scale.
On an Indian plate, refined grain, sugar and fried snacks are usually where the extra calories hide. Fill half the plate with sabzi or salad, a quarter with dal, paneer, eggs, fish or chicken, and size the rice or rotis to your body and your day. The trial's 150 minutes of activity is a little over 20 minutes a day, and a brisk walk after dinner is the easiest place to find it.