Gestational Diabetes Calculator
Assess gestational diabetes risk factors, check glucose readings against ACOG/ADA targets, and get meal planning guidance.
About this calculator
This calculator assesses gestational diabetes (GDM) risk factors and checks your glucose readings against ACOG's published pregnancy glucose targets (ACOG Practice Bulletin No. 190, consistent with ADA guidance). GDM Risk Score accumulates points from four factors: Age (2 points at 35+, 1 point at 30+), Pre-Pregnancy BMI (3 points at 30+, 1 point at 25+), Family History of Diabetes (2 points), and Previous Gestational Diabetes (3 points), then sorts the total into Risk Category -- Low (0-2 points), Moderate (3-5), or High (6 or more). Fasting vs. Target and 1-Hour vs.
Target simply subtract the ACOG/ADA targets (95 mg/dL fasting, 140 mg/dL one hour after eating) from whatever you enter for Fasting Glucose and 1-Hour Post-Meal Glucose -- each of those two delta figures responds only to its own matching glucose input and to nothing else, since Age, BMI, and the two yes/no history questions play no role in the glucose-target comparison. Fasting Glucose Above Target and 1-Hour Glucose Above Target flag whether either reading exceeded its target. Daily Carb Target, Carbs Per Main Meal, and Carbs Per Snack scale down as Pre-Pregnancy BMI rises (175g at BMI 30+, down from 210g under 25), reflecting more conservative carbohydrate guidance for higher-BMI pregnancies. This tool applies general clinical screening criteria -- an actual GDM diagnosis requires a formal glucose tolerance test interpreted by your provider.
Medical Disclaimer
This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.
Inputs
Results
GDM Risk Score
2
Figures current as of 2018. Source: American College of Obstetricians and Gynecologists (ACOG). Practice Bulletin No. 190: Gestational Diabetes Mellitus. Obstetrics & Gynecology. 2018;131(2):e49-e64.
How to Use This Calculator
- Enter Age, Pre-Pregnancy BMI, and Fasting Glucose.
- Set 1-Hour Post-Meal Glucose, Family History of Diabetes, and Previous Gestational Diabetes.
- Review the GDM Risk Score result.
- Use Risk Category (0=Low, 1=Moderate, 2=High) and Fasting Glucose Above Target to inform your decision.
How the result changes with Age
| Age | GDM Risk Score |
|---|---|
| 15 | 1 |
| 23 | 1 |
| 45 | 3 |
| 55 | 3 |
What each input means
- Age
- Your age at time of pregnancy. Risk increases after age 30.
- Pre-Pregnancy BMI
- Body mass index before pregnancy. BMI >= 30 is a major risk factor.
- Fasting Glucose
- Blood glucose after overnight fast. Target < 95 mg/dL in pregnancy.
- 1-Hour Post-Meal Glucose
- Blood glucose 1 hour after eating. Target < 140 mg/dL.
- Family History of Diabetes
- Enter 1 if a first-degree relative has type 2 diabetes, 0 otherwise.
- Previous Gestational Diabetes
- Enter 1 if you had gestational diabetes in a prior pregnancy, 0 otherwise.
What each result means
- GDM Risk Score
- Cumulative risk points based on age, BMI, family history, and prior GDM (0-11 scale).
- Risk Category (0=Low, 1=Moderate, 2=High)
- 0 = Low (0-2 pts), 1 = Moderate (3-5 pts), 2 = High (6+ pts).
- Fasting Glucose Above Target
- 1 if fasting glucose exceeds the 95 mg/dL target.
- 1-Hour Glucose Above Target
- 1 if 1-hour post-meal glucose exceeds the 140 mg/dL target.
- Fasting vs. Target
- Difference from the 95 mg/dL fasting target. Positive = above.
- 1-Hour vs. Target
- Difference from the 140 mg/dL post-meal target. Positive = above.
- Daily Carb Target
- Recommended daily carbohydrate intake based on pre-pregnancy BMI.
- Carbs Per Main Meal
- Suggested carbohydrate amount per main meal (3 meals/day).
- Carbs Per Snack
- Suggested carbohydrate amount per snack (3 snacks/day).
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersAge = 30, Pre-Pregnancy BMI = 25, Fasting Glucose = 85, 1-Hour Post-Meal Glucose = 130 = 6 input(s) provided
- Calculate GDM Risk ScoreGDM Risk Score2 = 2
- Calculate Risk CategoryRisk Category0 = 0
- Calculate Fasting Glucose Above TargetFasting Glucose Above Target0 = 0
Figures and sources
- ACOG glucose targets and risk factors for gestational diabetes management (2018) — American College of Obstetricians and Gynecologists (ACOG). Practice Bulletin No. 190: Gestational Diabetes Mellitus. Obstetrics & Gynecology. 2018;131(2):e49-e64.
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
What determines my Fasting vs. Target result?
Fasting vs. Target is simply your entered Fasting Glucose reading minus the fixed 95 mg/dL target published in ACOG Practice Bulletin No. 190 on gestational diabetes -- it responds only to the Fasting Glucose input you provide. Age, BMI, family history, and previous GDM status have no bearing on this figure at all, since it is a direct comparison of one glucose reading against one fixed clinical target.
How is my GDM Risk Score calculated?
GDM Risk Score adds points from four independent factors: Age contributes 2 points at 35 or older (1 point at 30-34), Pre-Pregnancy BMI contributes 3 points at 30 or above (1 point at 25-29.9), Family History of Diabetes contributes 2 points if present, and Previous Gestational Diabetes contributes 3 points if present -- the total then sets your Risk Category as Low, Moderate, or High.
Why does my recommended Daily Carb Target change with BMI?
Daily Carb Target uses a tiered scale based on Pre-Pregnancy BMI: 210g for a BMI under 25, 195g for 25 to 29.9, and 175g at 30 or above. This reflects general GDM nutrition guidance that recommends somewhat more conservative carbohydrate intake for pregnancies starting at a higher BMI, though the calculator always respects a 175g minimum regardless of how high BMI goes.
Does having a family history of diabetes change my glucose target comparisons?
No. Family History of Diabetes and Previous Gestational Diabetes only feed into GDM Risk Score and Risk Category -- they have no effect on Fasting vs. Target, 1-Hour vs. Target, or either Above Target flag, which compare only your entered glucose readings against the fixed ACOG/ADA numeric targets.
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