Gestational diabetes mellitus, almost always called GDM, is glucose intolerance that is first recognised during pregnancy. The placenta releases hormones that make the mother's body less sensitive to insulin so that more glucose stays in the blood and reaches the baby. In a healthy pregnancy the pancreas keeps up by making extra insulin. In GDM it cannot, and blood sugar drifts higher than the safe range.

GDM is different from pre-existing type 1 or type 2 diabetes that was simply not diagnosed before pregnancy. That distinction matters because true GDM usually resolves after delivery while pre-existing diabetes does not. Either way, the management during pregnancy looks similar, and the goal is the same — keep maternal glucose in a tight range so the baby grows normally and you stay safe through labour and the postpartum period. The same focus on weekly milestones in our week-by-week pregnancy guide helps you see where GDM screening fits in your overall timeline.

Hospital and community studies across India report a GDM prevalence of roughly 10 to 20 percent of all pregnancies, depending on the population and how aggressively women are screened. That is much higher than the global average of around 6 percent. South Asian women are genetically more insulin-resistant at any given BMI, carry more visceral fat for the same body weight and often have first-degree relatives with type 2 diabetes — all of which raise the baseline risk before pregnancy even begins.

Layered on top of that are modern risk factors many urban Indian women now face: later age at first pregnancy, higher pre-pregnancy BMI, polycystic ovary syndrome, lower physical activity, and refined-carbohydrate-heavy diets. If you have one or more of these — age over 30, BMI over 25, PCOS, a parent or sibling with diabetes, a previous baby weighing over 3.5 kg, or a previous GDM pregnancy — your obstetrician will almost certainly recommend OGTT screening at the first antenatal visit and again at 24 to 28 weeks rather than waiting. Women managing PCOS may also recognise overlap with the dietary themes in our anti-PCOS diet guide, since insulin resistance is at the centre of both conditions.

The Diabetes In Pregnancy Study group of India (DIPSI) recommends universal screening with a 75g oral glucose tolerance test at 24 to 28 weeks of pregnancy for every Indian woman, regardless of risk factors. Women at high risk are also screened at the first antenatal visit and rescreened later if that early test is normal. The 75g OGTT remains the global gold standard endorsed by WHO and FIGO and is the same test used for non-pregnant glucose testing, just interpreted with stricter pregnancy cutoffs.

The test takes about two and a half hours and follows a clear sequence. You fast for at least 8 hours overnight, drink only water, and reach the lab in the morning. A fasting venous blood sample is drawn. You then drink 75 grams of glucose dissolved in about 250 to 300 ml of water within 5 minutes — it is intensely sweet and many women feel mildly nauseous, which is normal. Two more blood samples are drawn exactly 1 hour and 2 hours after the drink. You should sit quietly during the wait, not eat or smoke, and tell the technician if you vomit, because that may invalidate the test. Most government CHCs and PHCs do this test free of cost while private labs charge anywhere from 500 to 1500 rupees. Your routine scans, labs and reports will include this OGTT as a standard antenatal test.

• Macrosomia, where the baby grows larger than 4 kg, which raises the risk of difficult delivery, caesarean section and shoulder dystocia.
• Birth injury such as shoulder dystocia, clavicle fracture or brachial plexus injury when a large baby is delivered vaginally.
• Neonatal hypoglycemia in the first 24 to 48 hours after birth, because the baby's pancreas, having grown used to high maternal sugar, keeps making extra insulin after the umbilical cord is cut.
• Preeclampsia and pregnancy-induced high blood pressure, which are more common in women with poorly controlled GDM and can force an early delivery.
• Polyhydramnios, neonatal jaundice and respiratory distress, all more frequent in pregnancies with persistently high maternal glucose.
• Long-term metabolic risk for both mother and child: about half of women with GDM develop type 2 diabetes within 10 years, and their children carry a higher lifetime risk of obesity and type 2 diabetes.

Diet is the first treatment for GDM and works for roughly 70 percent of women without any medication. The Indian challenge is real, however — much of our staple diet is carbohydrate-heavy, and meals are often built around white rice, maida roti or refined wheat. The goal is not to remove carbohydrates but to switch to lower glycaemic index versions, shrink portions and pair every carbohydrate with protein, fibre and some healthy fat so the glucose release is slower.

Practical Indian swaps work better than rigid diet sheets. Replace white rice with brown rice, hand-pounded rice or millets such as ragi, jowar or bajra. Swap maida or refined wheat roti for whole wheat with added bran or millet flour. Cut total daily added sugar to under 25 grams and treat sweets, jam, fruit juice, soft drinks and mithai as rare exceptions rather than daily items. Add a fist-sized portion of protein at every main meal: dal, paneer, dahi, sprouts, eggs or, if non-vegetarian, chicken or fish. Fill at least half the plate with non-starchy vegetables and a salad with lemon or amla for vitamin C.

Portion control matters more than any single food. A useful guide: if you used to eat one cup of cooked rice, switch to half a cup; if you used to eat two rotis, drop to one roti with extra sabzi and protein. Spread food across three main meals and three small snacks rather than two large meals — small frequent meals keep glucose much steadier. Choose low-GI fruits like apple, pear and guava in measured portions, and limit mango, banana, chikoo and grapes. Many of the principles overlap with our Indian superfoods during pregnancy guide, which adds nutrient density to the same lower-GI framework.

• Aim for at least 30 minutes of moderate activity on most days. A brisk walk after each main meal is the most evidence-based single step — even 10 to 15 minutes of walking within an hour of a meal blunts the glucose spike measurably.
• Prenatal yoga is excellent for GDM. Choose seated and standing postures with breath work, gentle hip openers and supported reclining poses; avoid deep twists, lying flat on the back after the second trimester and any pose that compresses the abdomen.
• Swimming and water aerobics are joint-friendly, easy on the back and safe through all trimesters if your obstetrician approves and the pool water is clean.
• Light resistance training with body weight or 0.5 to 1 kg dumbbells helps muscle take up glucose more efficiently. Two short sessions a week of squats to a chair, wall push-ups and seated rows are a sensible starting point.
• Stop and consult your doctor immediately if you experience contractions, vaginal bleeding, leaking fluid, severe breathlessness, chest pain or dizziness during activity. Our guide on movement and stretching across trimesters has trimester-specific routines you can pair with GDM management.

If your glucose targets are not met after one to two weeks of consistent diet and movement, your obstetrician will add medication. The default in pregnancy is insulin. Insulin is a large molecule that does not cross the placenta in any meaningful amount and is therefore considered the safest glucose-lowering drug in pregnancy worldwide. It is given as an injection under the skin with a fine pen needle, usually once at bedtime to control fasting glucose and additional short-acting doses before meals if post-meal numbers are high.

Starting insulin can feel frightening because many Indian families associate it with severe end-stage diabetes. In GDM the opposite is true: insulin is the gentlest, most predictable tool we have, the dose is tiny compared with type 2 diabetes, and most women stop insulin completely within hours of delivery. Your team will teach you the injection technique, rotation of sites such as belly, outer thigh and upper arm, safe storage in the fridge, and how to recognise low blood sugar (hypoglycemia) and treat it quickly with glucose tablets, juice or sugar.

Oral metformin, often sold in India under the brand name Glycomet, is sometimes used as an alternative or add-on in GDM, particularly when insulin is refused or impractical. It does cross the placenta but large studies have not shown harm to babies in the short term. Long-term follow-up is still emerging, and many Indian obstetricians prefer insulin first, reserving metformin for selected cases. Whichever drug is chosen, the goal is the same — bring fasting glucose under 95 mg/dL and 1-hour post-meal glucose under 140 mg/dL with the fewest side effects.

Once GDM is diagnosed, home monitoring becomes part of your daily routine. The standard schedule is four finger-prick checks a day with a personal glucometer: one fasting first thing in the morning, and one at 1 hour after the start of each main meal. Typical targets are fasting under 95 mg/dL and 1-hour post-meal under 140 mg/dL, though your obstetrician may tighten or relax these based on your case.

Write the readings in a simple notebook or app, along with what you ate, so patterns become visible. If a particular meal — say, the family Sunday biryani or a wedding feast — consistently spikes your numbers, that is information to discuss at the next visit. HbA1c, which reflects average glucose over the past 8 to 12 weeks, is usually checked once or twice during pregnancy as a supportive number rather than the main decision-maker, because HbA1c is less reliable in pregnancy due to faster red blood cell turnover.

Growth scans become more frequent in GDM, typically every three to four weeks in the third trimester instead of once. The sonographer estimates fetal weight, abdominal circumference and amniotic fluid volume, looking for macrosomia or polyhydramnios. If the baby is tracking large or fluid is rising, your obstetrician may tighten glucose targets, adjust insulin or plan delivery a little earlier.

For most women, GDM resolves within hours to days of delivery as placental hormones disappear and insulin sensitivity returns to normal. Insulin is usually stopped immediately after birth, and glucose is checked a few times in the first 24 to 48 hours to make sure numbers are stable. Your baby will also have a heel-prick glucose check in the first day to rule out neonatal hypoglycemia.

The single most important step after a GDM pregnancy is a repeat 75g OGTT at 6 to 12 weeks postpartum. This test reclassifies you as normal, prediabetic or diabetic and is critical because about half of women with GDM develop type 2 diabetes within the next 10 years. If the postpartum OGTT is normal, the recommendation is still annual HbA1c or fasting glucose for life, ongoing healthy weight and activity, and full screening before any future pregnancy. If it is prediabetic or diabetic, lifestyle changes plus medication can prevent or delay progression. Many women miss this test because they feel completely well after delivery — please do not miss it.

Breastfeeding, often supported by elders in the family and the wider community we explore in building your village of support, actively improves the mother's insulin sensitivity and reduces long-term diabetes risk for both mother and baby — another good reason to prioritise it after a GDM pregnancy.

• Cost of the OGTT itself is modest — government CHCs and PHCs offer it free, while private labs charge roughly 500 to 1500 rupees. A personal glucometer costs around 1000 to 2500 rupees one-time, with test strips at 15 to 25 rupees per strip, so home monitoring runs about 1500 to 3000 rupees per month at four checks a day.
• Insulin is widely available and government schemes such as PMJAY and many state programmes cover it for eligible women. Insulin pens and disposable needles cost roughly 100 to 250 rupees each and last several days at typical GDM doses.
• Family pressure to eat for two is one of the biggest practical challenges in Indian GDM. Bringing your mother-in-law, mother or partner to a nutrition counselling session — once if your hospital offers it — is far more effective than arguing about portions at home. Showing them your glucometer readings often shifts the conversation faster than any explanation.
• Festivals, weddings and family functions are unavoidable. Plan ahead: eat a small protein-rich snack before the event so you do not arrive hungry, fill the plate with salad and sabzi first, take only a token portion of mithai or biryani, and walk for 10 to 15 minutes after the meal. One indulgent meal will not derail control if the next meal returns to plan.
• Doctor red flags — call your obstetrician immediately if you have repeated glucose readings above 200 mg/dL, persistent vomiting that prevents eating, ketones detected on a urine strip, severe headache or visual disturbance, or noticeably decreased fetal movement.

Gestational diabetes in India is common, manageable and largely beatable with information and small daily habits. The 75g OGTT at 24 to 28 weeks is a non-negotiable test for every Indian pregnancy, and the cutoffs of 92, 180 and 153 mg/dL are worth knowing. If you are diagnosed, an Indian-context diet built around millets, dal, vegetables, protein and tight portions, combined with daily walking, gentle yoga and home glucometer checks, controls roughly seven in ten cases without any medication. If you need insulin, it is safe, predictable and almost always stops at delivery.

The single step women most often miss is the 6-week postpartum OGTT. Put it in your phone calendar before you leave the hospital with your baby. Your future self — and the half of women with GDM who would otherwise develop type 2 diabetes within a decade — will thank you for that one appointment.