QUESTION: My first pregnancy was uncomplicated, but at 33 weeks in my second pregnancy my blood sugar was 210 mg/dL. My doctor advised food changes, exercise, and insulin. My readings are now within target. Why did gestational diabetes occur this time? Did I cause it, and how do pregnancy adaptations affect me and my baby?
You did not cause gestational diabetes by eating one particular food or doing something wrong. Each pregnancy is different. Placental hormones naturally make the body more resistant to insulin, especially in the third trimester. Gestational diabetes develops when the pancreas cannot make enough extra insulin to overcome that resistance. A reading of 210 mg/dL is high, so continue monitoring and do not decline prescribed insulin without discussing your complete glucose log with the maternity team.
Answer by Dr. Albana Greca, MD, MMedSc
Having a normal first pregnancy does not guarantee that glucose will remain normal in later pregnancies. Insulin resistance may be stronger during a later pregnancy, and the body's insulin-producing capacity may change with age, weight, activity, family history, polycystic ovary syndrome, or underlying prediabetes.
Gestational diabetes can also occur without obvious risk factors. It is not proof that you ate too much sugar, and blame is neither accurate nor helpful.
During pregnancy, the placenta produces hormones that help direct nutrients to the growing baby. These hormones also reduce the mother's sensitivity to insulin. This is a normal physiologic adaptation and becomes more pronounced later in pregnancy.
Most pregnant people produce enough additional insulin to keep glucose within range. Gestational diabetes occurs when that compensation is insufficient. The adaptation itself is normal; the resulting high glucose requires treatment.
A value of 210 mg/dL is well above pregnancy glucose targets. Its exact meaning depends on whether it was fasting, after a meal, or part of a formal glucose-tolerance test, but it should not be dismissed because later readings improved.
Common pregnancy targets are below 95 mg/dL fasting, below 140 mg/dL one hour after eating, or below 120 mg/dL two hours after eating. Use the timing and targets given by your own maternity team.
Food changes and safe activity may be enough for some women, while others need insulin. Insulin is used when glucose remains above pregnancy targets and does not cross the placenta.
Do not decide independently to refuse, delay, start, stop, or change insulin. Send your complete fasting and after-meal log to the prescribing clinician. If all readings are consistently within target, the clinician can determine whether lifestyle treatment alone is sufficient or insulin is still needed.
Extra maternal glucose crosses the placenta and may cause the baby to produce more insulin and grow larger. Poorly controlled gestational diabetes can increase the likelihood of:
These are increased risks, not predictions. Good control during the remaining weeks can still reduce complications.
Gestational diabetes raises the risk of high blood pressure, preeclampsia, induction of labor, cesarean birth, and gestational diabetes in a future pregnancy. It also reveals a higher lifetime risk of prediabetes and type 2 diabetes.
Your obstetric team may monitor blood pressure, fetal growth, amniotic fluid, fetal movement, and the baby's well-being more closely. Delivery timing should be individualized according to glucose control, medicines, fetal growth, and other pregnancy findings.
Our guide to gestational diabetes treatment explains food, monitoring, activity, and medicine options.
Glucose often improves rapidly after the placenta is delivered, but gestational diabetes is not considered permanently “cured.” A 75-gram oral glucose tolerance test is recommended 4–12 weeks after delivery. If normal, diabetes screening should continue every one to three years.
Breastfeeding is encouraged when possible. Healthy food, activity after recovery, and reaching a suitable postpartum weight may reduce future type 2 diabetes risk.
Contact the maternity unit immediately for reduced fetal movement, vaginal bleeding, leaking fluid, regular painful contractions, severe headache, vision changes, pain under the right ribs, sudden swelling, or very high glucose with vomiting or ketones. Do not wait for the next routine appointment when these symptoms occur.
Gestational diabetes in a second pregnancy is not a personal failure. Your improved readings are encouraging, but a previous value of 210 mg/dL warrants continued close follow-up. Let the maternity team—not a few isolated readings—decide whether insulin is needed and how the pregnancy should be monitored.
Educational safety note: This answer is for general diabetes and pregnancy education only. It does not replace personal obstetric or diabetes care. Do not start, stop, refuse, or change insulin, tablets, supplements, food intake, or activity without speaking with your maternity team.
Last reviewed: July 2026.
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