Ramadan Fasting and Gestational Diabetes Diagnosis in Pregnant Women: What the Research Shows

Ramadan Fasting and Gestational Diabetes Diagnosis in Pregnant Women: What the Research Shows

A large Spanish study looked at over 35,000 pregnancies to see if fasting during Ramadan changes gestational diabetes test results. Among women from Muslim-majority countries, 12.8% were diagnosed with gestational diabetes during Ramadan, compared with 8.84% at other times. Women from other backgrounds showed almost no difference. Researchers think testing timing, not just fasting, may explain this gap.

Medical disclaimer: This article summarises published research for informational purposes only. It is not medical advice and is not a substitute for guidance from a qualified health professional. Always consult your doctor before starting any fasting protocol, especially if you have an existing health condition or take medication.

The Short Version

• What they tested: whether fasting during Ramadan changes how gestational diabetes (diabetes that can develop during pregnancy) gets diagnosed.
• Who did it: M. Carrasco at University Hospital Arnau de Vilanova, published in BMC Medicine in 2026.
• How many people: 35,054 pregnancies, all women, ages 18 to 50.
• How long: nine years of health records, from 2010 to 2019.
• What happened: diagnosis rates were higher during Ramadan, but only in one group of women.
• Read the study yourself: BMC Medicine 2026 →

What They Wanted to Find Out

Gestational diabetes is diabetes that shows up during pregnancy and goes away after birth. Doctors test for it with a blood sugar test. Researchers wanted to know if Ramadan fasting changes how many women get that diagnosis. This matters for the roughly 2 billion people who observe Ramadan worldwide, many of them pregnant women.

Other studies on this site have looked at how Ramadan fasting affects blood sugar and insulin in healthy adults and heart health markers. This study asked a different question: does the timing of the test itself change the result during a fasting month?

Who Was in the Study

Who they were: 35,054 pregnancies in total, all women, ages 18 to 50. None had diabetes before pregnancy. They lived in Catalonia, Spain, and were matched by age across the two groups.

What the fasting actually looked like: Ramadan is a month where observant Muslims do not eat or drink from sunrise to sunset. The researchers did not assign anyone to fast. They simply compared test results from times when Ramadan happened to fall during a pregnancy against other times of year.

What Happened

Women from Muslim-majority countries were diagnosed with gestational diabetes more often during Ramadan than at other times of year.

• About 1 in 8 women from Muslim-majority countries were diagnosed during Ramadan.
• That compares to fewer than 1 in 11 at other times, in the same group.
• The comparison group's diagnosis rate barely moved by time of year.
• A further check that accounted for age, weight, blood pressure and income still showed the same pattern.
• The researchers said this gap was unlikely to be chance.

What Did Not Change

• The comparison group's diagnosis rate stayed almost flat across the year.
• Nothing in the abstract suggests actual blood sugar control got worse during Ramadan — only the diagnosis rate changed.
• Muscle, body weight and other physical measurements were not reported in this study.

What the Researchers Said

The research team said the higher diagnosis rate during Ramadan may come from fasting itself, or from changes in how and when tests are scheduled. They said doctors should think about Ramadan timing when planning gestational diabetes screening.

What This Means for You

• If you are pregnant during Ramadan, ask your doctor about the best timing for your diabetes test.
• This study cannot tell you if fasting itself raises blood sugar — only that diagnosis rates were higher during Ramadan.
• Women from Muslim-majority countries showed the biggest difference in this study; other women did not.
• Test timing may matter as much as fasting. The researchers pointed to testing practices, not just the fast, as a possible cause.
• For more on Ramadan and women's hormones, see Ramadan fasting and menopause hormones.
• For a different angle on fasting and women's blood health, see fasting and iron levels in women.

What This Study Could Not Tell Us

• This was not a controlled trial. Researchers did not decide who fasted and who didn't.
• It cannot say for certain that fasting — rather than something else — caused the gap.
• It only looked at records from Catalonia, Spain. Results could differ elsewhere.
• It did not report how many women in the Muslim-majority group actually fasted.
• The abstract does not report who funded the study.

The Study Details

Carrasco, M., Vlacho, B., Franch-Nadal, J., Real, J., Monroy, G., Soldevila, B., et al. (2026). Overdiagnosis of gestational diabetes mellitus during Ramadan: a retrospective population-based study in Catalonia, Spain. BMC Medicine. PMID: 41559733

Common Questions

Does fasting during pregnancy cause gestational diabetes?

This study did not test that directly. It looked at whether diagnosis rates changed during Ramadan, not at the cause of diabetes itself.

Is it safe to fast during Ramadan while pregnant?

The study did not test safety directly. It found diagnosis rates rose during Ramadan in one group. Talk to your doctor before deciding whether to fast while pregnant.

Why would diagnosis rates go up during Ramadan?

Researchers think it could be the fasting itself, or changes in how and when glucose tests are scheduled during Ramadan.

Did fasting affect women from non-Muslim-majority countries the same way?

No. Their diagnosis rate barely changed, from 5.52% outside Ramadan to 5.57% during it.

How many women were in this study?

The study included 35,054 pregnancies, all screened for gestational diabetes, across nine years of health records.

More Research Like This

• Ramadan Fasting Lowers Insulin and Improves Insulin Sensitivity (how well the body handles sugar) in Healthy Men
• Ramadan Fasting Reduces Blood Pressure, Cholesterol, and Blood Sugar
• Ramadan Fasting Increases Beneficial Gut Bacteria by Up to 73% in 30 Days
• Two-Day Fasting Cycles Lowered Iron and Hemoglobin in Healthy Women
• Ramadan Fasting and Menopause Hormones
• 5:2 Intermittent Fasting Improved Menstrual Regularity in 80% of Obese Women With PCOS
• Longer Overnight Fasting Was Linked to Higher Gallstone Hospitalization Risk in Women

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