Gestational diabetes: food diary and carbohydrate counting
A diary for gestational diabetes is not about self-discipline or “try writing things down.” The 2024 Russian clinical guidelines require everyone who is pregnant with this diagnosis to keep one, recording more than food: glucose, and the time and type of physical activity. A doctor uses this diary to decide whether nutrition is sufficient or insulin therapy is needed—so what is in it affects treatment.
What the guidelines actually require
The 2024 Russian Ministry of Health clinical guidelines on gestational diabetes mellitus state this directly: everyone pregnant with gestational diabetes is advised to keep a self-monitoring diary recording capillary blood glucose values, dietary details, and the time and type of physical activity.
All three belong together, rather than separately. Glucose without food shows the result but not the cause. Food without glucose is effort without feedback. A walk after dinner changes the number an hour later; without it, the result looks like an unexplained failure.
Target values in the same guidelines are:
| When | Target value |
|---|---|
| Fasting | below 5.1 mmol/L |
| One hour after eating | below 7.0 mmol/L |
| Two hours after eating | below 6.7 mmol/L |
The post-meal number is the only place where you can see what a particular plate did. That is why the diary is built around pairs of “what I ate—what number I got,” rather than a daily total.
Why carbohydrates, not calories, are counted
The calorie content of a dish does not predict a rise in glucose: cheese and porridge with the same calorie content behave differently. Post-meal glucose is affected primarily by the amount and quality of carbohydrates, which is why they are counted.
This leads to a common mistake: deciding that, because carbohydrates raise blood sugar, they should be removed. The guidelines set a lower limit—175 g of carbohydrates a day or at least 40% of the diet—while excluding carbohydrates with a high glycemic index. Below that threshold, ketonuria begins, so the same guidelines call for monitoring urine ketones to identify it promptly.
The task, then, is not “fewer carbohydrates,” but “the same amount, of different kinds and distributed differently.” These are different tasks, and the second is noticeably harder—the diary is there to support it.
How carbohydrates are distributed through the day
A review of national nutrition guidelines for gestational diabetes, which compared guidance from different countries, found a shared approach: carbohydrates are distributed across three main meals and two or three snacks, with preference given to foods high in fiber and low on the glycemic index.
The practical consequence is that breakfast is usually the hardest meal: insulin sensitivity is lower in the morning, so the same porridge that stays within range at lunch can produce a number above target in the morning. This is visible only in a diary, and only if the meal time is recorded.
What makes the same weight of carbohydrates differ in absorption speed is covered separately in the article on the glycemic index.
What to write for the diary to help your doctor
A diary that says “breakfast: porridge” answers no question. A useful entry is a line that lets a meal be repeated—or not repeated:
| Field | Example |
|---|---|
| Time | 8:15 |
| What | Oatmeal made with water, an egg, half an apple |
| How much | 200 g oatmeal, 1 egg, 90 g apple |
| Carbohydrates | about 42 g |
| Glucose one hour later | 7.4 |
| Activity | — |
The line above is actionable: the number is above target, and it is clear what may have caused it. Next, change one thing—the breakfast composition, portion weight, or time—and the same breakfast a day later shows whether it helped. Physical activity also affects the post-meal number, but its amount during pregnancy should be agreed with a doctor, not chosen from the diary.
Writing from memory in the evening is a common and costly habit. Not because it is lazy, but because reconstructing a day in the evening systematically loses small details: a spoonful of oil in porridge, juice, a biscuit with tea. In the diary, this looks like an inexplicably high number after “the right” food.
Where the count most often breaks down
- Dry weight instead of cooked weight. Grains take up water when cooked, and carbohydrates per 100 g fall three- to fourfold. Applying a reference value for dry buckwheat to a plate of cooked buckwheat inflates the count many times over. The gap is covered separately in the article on dry versus cooked weight.
- Sauces and dressings. Ketchup, ready-made sauces, and “light” yogurt dressings contain sugar that is not in the dish name.
- “Diabetic” and “sugar-free.” A package claim does not mean low carbohydrate content: a sweetener often appears alongside flour and starch. What these claims mean is covered in the article on diabetic foods.
- Estimating by eye. Visual weight estimates are systematically wrong in one direction: they underestimate. Data on this discrepancy are given in the article on carbohydrate exchange units.
How to count faster and keep going
People abandon a diary not because the arithmetic is difficult, but because there is so much of it: three meals and two snacks mean five entries every day, for months. What reduces the work:
- Weigh your five usual portions once. Your normal bowl of porridge, usual slice of bread, glass of milk, spoonful of oil, and apple. Then visual estimation uses familiar reference points rather than abstractions. The method is described in the article on portion size without scales.
- Read the label, not a reference table. For packaged food, carbohydrates are stated on the package, which is more accurate than any average value.
- Repeat what already worked. A breakfast after which your number stayed within target is a ready-made solution, not a one-off success. A few such breakfasts cover the hardest time of day without recalculating every day.
- Do not count what does not count. Vegetables, greens, and protein dishes have almost no effect on the overall carbohydrate count, and precision adds nothing here.
Analyzing a meal from a photo gives carbohydrates along with the other macros, leaving only the number and time to put in the diary. It is an estimate, not a measurement: each plate has its own recipe, so adjust the portion weight manually if it differs from what is on the table.
What the diary does not solve
A diary shows what is happening, but does not prescribe treatment. If nutrition does not bring values within target, the guidelines provide for insulin therapy; that is a doctor’s decision, made in part from the diary entries rather than instead of them. You should not change anything other than food and walks on your own based on diary numbers.
Nor does it assess weight gain or replace scheduled appointments. It answers one question: what food, in what amount, stays within your target specifically for you. It answers this better than any general table because it works from your own numbers.
Frequently asked questions
- Is a food diary required for gestational diabetes?
- The 2024 Russian Ministry of Health clinical guidelines call for every pregnant person with gestational diabetes to keep a self-monitoring diary that records blood glucose, dietary details, and the time and type of physical activity.
- How many carbohydrates a day are allowed with gestational diabetes?
- The guidelines give a lower limit: 175 g of carbohydrates a day or at least 40% of the diet, while excluding foods with a high glycemic index. Cutting carbohydrates lower is dangerous because ketonuria develops, which is monitored separately with a urine test.
- How long after eating should glucose be measured?
- Target values are specified for two points: below 7.0 mmol/L one hour after eating and below 6.7 mmol/L two hours after eating. The fasting target is below 5.1 mmol/L. Your supervising doctor decides which time point to use.
- Why is blood sugar sometimes in range after the same porridge and sometimes above it?
- Most often, it comes down to time of day and what accompanied it. Insulin sensitivity is lower in the morning, so breakfast can give a higher number than the same food at lunch. Portion weight, fat and protein in the same meal, and movement after eating also matter; that is why the diary records time and activity, not only food.
Read next
- Bread units: how to count them and who needs them today — A bread unit is a measure of carbohydrates designed to convert food into an insulin dose.
- Diet for type 2 diabetes: what diet comparisons have shown — Debates about diet for type 2 diabetes often focus on choosing the right diet.
- Glycemic index: what it measures and when it is useless to use — Glycemic index tables look like a list of allowed and forbidden foods: buckwheat has one number, potatoes have another, and it seems straightforward from there.
- Diabetic products: what changes in them besides the price — The label "for diabetic nutrition" describes one property of a product — it contains fewer simple sugars than its standard counterpart.
This article is for general information. It is not medical advice, a diagnosis, or a prescription for treatment or a diet, and it does not replace a consultation with your doctor. If you have a health condition, are pregnant, take medication, or follow a diet prescribed to you, decisions about food belong with your doctor.
Figures from regulations, guidelines and studies are given as they stood when this article was prepared and may since have changed; check them against the primary sources. This article is not advertising, an offer, or individual advice, and neither the author nor the site owner is responsible for decisions taken on the basis of it.