Gestational diabetes in plain language: diagnosis, management, and what to watch after birth

This article is for general information only, not medical advice. It has been reviewed by a clinician, but it is not a substitute for your own care team. If you have been diagnosed with gestational diabetes, or are concerned about your blood glucose readings, contact your midwife, obstetrician, or diabetes care team as soon as possible. For severe symptoms including confusion, dizziness, or signs of hypoglycemia, call emergency services or go to your nearest emergency department immediately. No app tool replaces clinical monitoring or the advice of your care team.

What is gestational diabetes, and why does it develop?

Gestational diabetes mellitus (GDM) is glucose intolerance that is first detected during pregnancy. It develops when the placenta produces hormones that block insulin, creating a state of insulin resistance. In most pregnancies, the pancreas compensates by producing more insulin. When it cannot keep up, blood glucose rises above the diagnostic threshold. Gestational diabetes resolves in the large majority of women after the placenta is delivered.

The condition is common and becoming more so. In 2023-24, nearly 1 in 5 women who gave birth in an Australian hospital, approximately 49,800 people, was diagnosed with gestational diabetes. (Gestational diabetes, Australian Institute of Health and Welfare, 2024) That figure has climbed for two decades. Rising obesity, older first-time mothers, and more IVF conceptions each push it up.

Gestational diabetes typically develops in the second half of pregnancy, when placental hormone production peaks. Most cases are detected at the routine 24 to 28 week oral glucose tolerance test (OGTT). The condition itself usually produces no noticeable symptoms, which is the main reason universal screening exists. By the time you feel anything different, blood glucose has often been elevated for some time.

Last reviewed: 10 September 2026.

Who is at higher risk of gestational diabetes?

A history of gestational diabetes in a prior pregnancy is the strongest single risk factor. A 2025 systematic review and meta-analysis pooled data from 30 studies and 30,524 women and found a recurrence rate of around 51 percent, with a range of 31 to 74 percent across populations. If you had gestational diabetes before, raise it at your first antenatal appointment so early screening can be arranged. (Bahreiny et al., GDM recurrence rate and risk factors: systematic review and meta-analysis, Diabetes Research and Clinical Practice, 2025, PMID 41130422)

Ethnic background matters a lot in Australia. Women of South Asian, East Asian, Polynesian, Middle Eastern, and Indigenous Australian background are diagnosed at higher rates than women of European background, and ADIPS lists each of these as a reason to screen early.

Other established risk factors include a BMI above 25 before pregnancy, age 35 or older, polycystic ovary syndrome (PCOS), a family history of type 2 diabetes in a first-degree relative, and conception via in vitro fertilisation or other assisted reproductive technologies. These factors stack. A first pregnancy at 37, with a BMI of 28 and a mother who had type 2 diabetes, is a different risk profile from any one of those on its own.

The Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study followed 25,505 women across nine countries and found no safe threshold below which maternal glucose stops affecting the baby. The relationship is a smooth curve, not a switch. Diagnostic thresholds are lines drawn by convention across that curve. (Metzger BE et al., Hyperglycemia and adverse pregnancy outcomes, NEJM 2008, PMID 18463375)

That is worth holding onto. A fasting result of 5.2 is not safe because it sits under 5.3, and a 5.4 is not a catastrophe because it sits above. The number tells you where you are on the curve. What you do next matters more than which side of the line you landed on.

How is gestational diabetes diagnosed?

Gestational diabetes is diagnosed in Australia using the 75 gram two-hour oral glucose tolerance test (OGTT), administered at 24 to 28 weeks of pregnancy for all women who do not already have a diagnosis of diabetes. You fast overnight, have a fasting blood glucose taken, drink a 75g glucose solution, then have blood taken again at one hour and two hours.

In June 2025, the Australasian Diabetes in Pregnancy Society published new consensus recommendations with updated diagnostic thresholds. Gestational diabetes is now diagnosed when any one of the following criteria is met on the 75g OGTT: a fasting plasma glucose of 5.3 mmol/L or higher, a one-hour plasma glucose of 10.6 mmol/L or higher, or a two-hour plasma glucose of 9.0 mmol/L or higher. (Australasian Diabetes in Pregnancy Society, ADIPS 2025 consensus recommendations, Medical Journal of Australia, PMID 40544364)

These thresholds are higher than the previous 2014 ADIPS criteria (which used fasting 5.1, one-hour 10.0, and two-hour 8.5 mmol/L) and higher than the IADPSG criteria that many other countries still apply. ADIPS raised them because the 2014 thresholds were diagnosing some women at limited clinical risk. Fewer women in Australia will be diagnosed as a result, mostly those with mildly elevated results.

A fasting plasma glucose of 7.0 mmol/L or higher, or a two-hour result of 11.1 mmol/L or higher, indicates overt diabetes in pregnancy rather than gestational diabetes, and is managed differently with more intensive care.

For women with a prior history of gestational diabetes, or an HbA1c in early pregnancy of 6.0 to 6.4 percent (42 to 47 mmol/mol), the 2025 ADIPS recommendations advise an early OGTT before 20 weeks, ideally at 10 to 14 weeks. This earlier test picks up pre-existing diabetes or high glucose while there is the most time to act on it.

If you had your OGTT before June 2025 and received a borderline result, ask your care team whether it would be read differently under the updated criteria.

Most articles you will find on this still quote the 2014 numbers. Check the date on anything you read.

What does a gestational diabetes diagnosis mean for the rest of your pregnancy?

A gestational diabetes diagnosis does not mean your pregnancy is automatically high-risk or that complications are inevitable. It means your blood glucose needs to be actively managed for the remainder of the pregnancy, and that you will have closer monitoring than you would have otherwise. Most women with gestational diabetes have good outcomes with appropriate management. (ACOG Practice Bulletin No. 190, Gestational Diabetes Mellitus, Obstetrics and Gynecology, 2018, PMID 29370047)

Management starts with checking your own blood glucose. The standard schedule is four readings a day: fasting (before your first meal) and one hour after each main meal. The 2025 ADIPS consensus addressed only the diagnostic thresholds shown in the table above. The blood glucose management targets were not changed. In Australian clinical practice the typical targets are a fasting result at or below 5.0 mmol/L and a one-hour post-meal result at or below 7.8 mmol/L. Your diabetes midwife or endocrinologist will confirm your specific targets at diagnosis, as they may be tighter depending on your pattern of results.

Medical nutrition therapy is the first-line treatment. This does not mean avoiding all carbohydrates. It means distributing carbohydrates through the day in controlled amounts, choosing lower glycaemic index foods, and pairing carbohydrates with protein and fat to blunt the glucose response. A dietitian who works with gestational diabetes belongs on your care team from this point. A 20 to 30 minute walk after meals also brings post-meal glucose down.

If blood glucose does not reach targets on medical nutrition therapy and activity alone, medication is added. In Australia, the two options are metformin (an oral tablet) and insulin (an injection). Insulin is the more effective of the two and is used first when glucose is well above target. Metformin crosses the placenta, and some women and care teams prefer insulin for that reason, though there is a large body of evidence on metformin in pregnancy. Your care team will guide this decision based on your specific results and preferences.

Monitoring of the baby’s growth also intensifies after a gestational diabetes diagnosis. Additional ultrasounds are common, particularly in the third trimester, to watch for macrosomia (a larger than average baby). Gestational diabetes also raises the risk of preeclampsia, so blood pressure checks continue at every visit. Depending on how well blood glucose is controlled and how the pregnancy progresses, your care team may recommend birth no later than 40 weeks. This timing discussion is worth having early, not in the final weeks.

What are the risks for the baby?

The main near-term risk from poorly controlled gestational diabetes is macrosomia, a baby that grows larger than the standard range, driven by the baby producing extra insulin in response to the elevated glucose passing through the placenta. A large baby increases the risk of difficult vaginal delivery, birth injuries, shoulder dystocia, and caesarean section. The HAPO study showed a clear, graded association between maternal glucose levels and large-for-gestational-age birth across the whole range of glucose values, below the diagnostic threshold as well as above it. (Metzger BE et al., HAPO study, NEJM 2008, PMID 18463375)

Neonatal hypoglycemia, low blood sugar in the hours after birth, is the other main risk in the first day. A baby whose pancreas has been stimulated to produce extra insulin during pregnancy continues to overproduce insulin briefly after delivery, before the glucose supply from the placenta stops. This can cause blood glucose to fall rapidly. Newborns of mothers with gestational diabetes are routinely monitored for hypoglycemia in the first hours after birth. Population-based cohort data have found an odds ratio of 11.71 for neonatal hypoglycemia in babies of mothers with gestational diabetes compared to those without. (What neonatal complications should the pediatrician be aware of in case of maternal gestational diabetes? PMC 2015, PMC4458502)

There are also longer-term risks for the child. The HAPO Follow-Up Study (HAPO FUS), which tracked children at age 10 to 14 years born to mothers in the original HAPO cohort, found that maternal gestational diabetes was associated with higher rates of childhood obesity, impaired glucose tolerance, and beta-cell dysfunction in the child, independent of other factors. (Lowe WL Jr et al., HAPO FUS, Diabetes Care 2019, PMID 30655380) That is the reason a borderline diagnosis is still worth taking seriously.

Good blood glucose control brings all of these risks down. The goal is not a perfect number on every reading. It is an average close enough to target that the baby’s pancreas is not being pushed all day, every day.

What happens after the birth?

In most cases, blood glucose returns to normal with delivery of the placenta. You are not classified as having gestational diabetes after the birth on the basis of the pregnancy diagnosis alone. But gestational diabetes tells you something about how much insulin your pancreas can make. That capacity may not keep up with normal aging, weight gain, or another pregnancy.

ADIPS recommends an OGTT at 6 to 12 weeks postpartum for all women who had gestational diabetes, to check for type 2 diabetes or prediabetes. After that, annual fasting glucose or HbA1c checks are advised for the long term.

A 2020 systematic review and meta-analysis of 170,139 women with gestational diabetes, covering 28 studies, found a pooled type 2 diabetes incidence of approximately 20 percent at 10 years after gestational diabetes. Women without gestational diabetes in the same studies had a roughly 2 percent rate. The relative risk of developing type 2 diabetes after gestational diabetes is approximately 10-fold. (Vounzoulaki E et al., Incidence of type 2 diabetes mellitus after gestational diabetes mellitus, PMC 2020, PMC7204113) That risk accumulates over decades.

You can move that number. Keeping weight steady after the birth, staying active, and getting glucose checked each year all lower the chance of conversion. Tell every GP you see in the years after this pregnancy that you had gestational diabetes, so the monitoring does not fall through the cracks.

What myCocoon tracks and does not track for gestational diabetes

Gestational diabetes management is centred on clinical care: a diabetes midwife or endocrinologist, a dietitian, a glucose meter, and a care plan. An app does not replace any part of that.

myCocoon tracks manually logged symptoms and weight. If you are recording gestational diabetes symptoms or noting how your readings are going, you can log those as symptoms or journal entries in the app. Weight readings you have recorded in the Apple Health app are read by myCocoon with your permission and stored in a part of the app that is set up to never sync to iCloud or CloudKit, following Apple’s HealthKit guidelines. Manually entered weight inside myCocoon syncs through your personal iCloud account.

The app does not read blood glucose readings from the Health app. A glucose number needs a meter, a care team, and a plan, not a card on a pregnancy app’s home screen.

When Cloud AI is on, your weight trend over the past four weeks is included in the daily summary sent to Google’s Gemini to give the assistant context about your pregnancy. Your raw Health app data beyond that daily summary is not sent. When Cloud AI is off, questions are answered by Apple Intelligence on your device or from pre-written information inside the app, and nothing leaves your phone. The privacy page names exactly what is and is not sent in each mode.

The assistant can answer questions about gestational diabetes diet, what your glucose targets mean, what to expect at an OGTT, and how to read your results. It is not a substitute for your diabetes care team’s advice, and it does not have your specific glucose readings unless you share them in a message to the assistant.

myCocoon is live on the App Store now, on iPhone with iOS 26 or later. It has no Android version and no peer community. What it gives you in the context of a gestational diabetes diagnosis is a place to track your symptoms, note how your readings are going in your journal, and ask questions when your care team is not available at 11pm.

Common questions

What are the new Australian gestational diabetes diagnosis thresholds? Australia moved to updated ADIPS 2025 criteria published in June 2025. Gestational diabetes is now diagnosed when fasting plasma glucose is 5.3 mmol/L or higher, one-hour glucose is 10.6 mmol/L or higher, or two-hour glucose is 9.0 mmol/L or higher on the 75g OGTT. These thresholds are higher than the previous 2014 ADIPS criteria, meaning fewer women will be diagnosed under the new guidelines.

When do you get tested for gestational diabetes? All pregnant women in Australia are advised to have a 75g oral glucose tolerance test at 24 to 28 weeks of pregnancy. Women with a prior history of gestational diabetes, or an early HbA1c of 6.0 to 6.4 percent (42 to 47 mmol/mol), are also advised to have an OGTT earlier in pregnancy, ideally between 10 and 14 weeks.

Can gestational diabetes go away on its own? Blood glucose usually returns to normal after delivery. Most women are no longer classified as having gestational diabetes once the placenta is delivered. However, gestational diabetes is a strong signal of underlying insulin resistance. ADIPS recommends an OGTT at 6 to 12 weeks postpartum and annual fasting glucose checks in the years that follow, because roughly 1 in 5 women who had gestational diabetes develops type 2 diabetes within 10 years.

Is gestational diabetes dangerous for the baby? Elevated blood glucose in pregnancy increases the risk of a large baby, neonatal hypoglycemia, preterm birth, and birth complications from a difficult delivery. Good blood glucose management brings these risks down a long way. Babies of mothers with well-controlled gestational diabetes generally have normal outcomes. A 2019 follow-up study found that children of mothers with gestational diabetes also carry a higher long-term risk of obesity and impaired glucose tolerance.

What is the difference between the Australian and US gestational diabetes thresholds? Since June 2025, Australia uses ADIPS 2025 thresholds: fasting 5.3, one-hour 10.6, and two-hour 9.0 mmol/L. The United States most commonly applies ACOG guidance, which allows either a one-step IADPSG approach (fasting 5.1, one-hour 10.0, two-hour 8.5 mmol/L) or a two-step approach using a one-hour 50g glucose challenge followed by a three-hour 100g OGTT. The same result can lead to different diagnoses depending on which country’s criteria apply.

Bottom line

Gestational diabetes was diagnosed in roughly 1 in 5 Australian hospital births in 2023-24 and the rate has been rising. Australia adopted updated ADIPS 2025 diagnostic thresholds in June 2025: fasting glucose 5.3 mmol/L or higher, one-hour 10.6 or higher, two-hour 9.0 or higher on the 75g OGTT. These are higher than the previous 2014 criteria, so if you had a borderline result under the old numbers, discuss with your care team.

If you have a prior history of gestational diabetes, a family history of type 2 diabetes, a BMI above 25, or a South Asian, East Asian, Polynesian, Middle Eastern, or Indigenous Australian background, raise it early so screening can be arranged before 20 weeks.

A gestational diabetes diagnosis calls for blood glucose self-monitoring, medical nutrition therapy with a dietitian, and regular clinical review. Most women manage to targets on diet and activity; insulin or metformin is added when needed.

After the birth, have the OGTT at 6 to 12 weeks and tell every GP in the years that follow. Roughly 1 in 5 women with gestational diabetes develops type 2 diabetes within 10 years. That risk is real, and you can lower it.

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