According to Gram Research analysis, measuring carbohydrates as a percentage of total daily calories—rather than just counting grams—is the most effective way to predict blood sugar control in type 2 diabetes. A 2026 cross-sectional study of 238 diabetic patients found that keeping carbs at 51.5% or less of daily calories optimized after-meal blood sugar, while 55.5% or less helped with fasting blood sugar. The Low Carbohydrate Diet scoring system was the second-best predictor of blood sugar control.
A new study of 238 people with type 2 diabetes found that measuring carbohydrates as a percentage of total daily calories works better than other methods for predicting blood sugar levels. Gram Research analysis shows that keeping carbs to 51.5% or less of your daily calories helps control blood sugar after meals, while staying at 55.5% or less helps with fasting blood sugar. The research also identified a scoring system called the Low Carbohydrate Diet (LCD) score that can help predict how well someone’s blood sugar will be controlled. These findings could help doctors and patients create more personalized eating plans that actually work for managing diabetes.
Key Statistics
A 2026 cross-sectional study of 238 people with type 2 diabetes found that keeping carbohydrates at 51.5% or less of total daily calories correctly identified 80.77% of people with good after-meal blood sugar control.
According to research reviewed by Gram, the Low Carbohydrate Diet score above 23.5 was the second-most effective predictor of after-meal blood sugar control in type 2 diabetes patients, with an accuracy of 71.53%.
A 2026 study comparing six carbohydrate measurement methods in 238 diabetic patients found that measuring carbs as a percentage of total calories was significantly more predictive of blood sugar control than simply counting total carb grams per day.
Research shows that fasting blood sugar control in type 2 diabetes improved when carbohydrate intake was limited to 55.5% or less of total daily calories, correctly identifying 66.47% of patients with good glycemic control.
The Quick Take
- What they studied: Which methods of measuring carbohydrate intake best predict blood sugar levels in people with type 2 diabetes
- Who participated: 238 adults with type 2 diabetes who had their blood sugar measured and their carbohydrate intake tracked
- Key finding: Measuring carbs as a percentage of total daily calories (not just counting grams) was the most accurate way to predict both fasting and after-meal blood sugar levels
- What it means for you: If you have type 2 diabetes, focusing on keeping carbs to about half your daily calories may help you control your blood sugar better than just counting carb grams. Talk to your doctor before making major diet changes.
The Research Details
Researchers looked at 238 people with type 2 diabetes and compared six different ways of measuring carbohydrate intake. They tested: total carbs eaten per day (in grams), carb portions, carbs as a percentage of total calories, a low-carb diet scoring system, the ratio of carbs to fiber, and total fiber intake. For each person, they measured two types of blood sugar: fasting blood sugar (measured before eating) and blood sugar after meals. They then used statistical analysis to see which carbohydrate measurement method was best at predicting each type of blood sugar reading.
This type of study is called cross-sectional, which means researchers collected all the information at one point in time rather than following people over months or years. The researchers used advanced statistical methods called logistic regression and ROC curve analysis to determine which measurement methods worked best.
Understanding which way to measure carbs is most useful helps doctors give better advice to their patients. If one measurement method is clearly better at predicting blood sugar control, patients can focus on that specific approach rather than trying multiple methods. This makes dietary management simpler and more effective.
This study has a reasonable sample size of 238 people, which is large enough to find real patterns. However, because it’s a cross-sectional study (a snapshot in time), it can’t prove that changing carb intake will definitely improve blood sugar—it only shows which measurements are connected to blood sugar levels. The study was published in a peer-reviewed journal, which means other experts reviewed it before publication. The results are specific to people with type 2 diabetes and may not apply to people without diabetes.
What the Results Show
The study found that measuring carbohydrates as a percentage of total daily calories was the strongest predictor of both fasting blood sugar and after-meal blood sugar. For after-meal blood sugar, the best cutoff was keeping carbs at 51.5% or less of total daily calories, which correctly identified 80.77% of people with good blood sugar control. For fasting blood sugar, the best cutoff was 55.5% or less of total daily calories, which correctly identified 66.47% of people with good control.
The Low Carbohydrate Diet (LCD) score was the second-best predictor. This score takes into account not just how many carbs someone eats, but also the quality of those carbs and other dietary factors. For after-meal blood sugar, an LCD score above 23.5 was most predictive, while for fasting blood sugar, a score above 16.5 worked best.
Other measurement methods—like simply counting total grams of carbs per day, measuring carb portions, looking at the carb-to-fiber ratio, or measuring fiber alone—were not as good at predicting blood sugar levels. This suggests that how much of your total calories come from carbs matters more than just the absolute amount of carbs you eat.
The research showed that higher carbohydrate percentages were significantly linked to worse blood sugar control. This means that as the percentage of calories from carbs increased, blood sugar levels tended to be higher and harder to control. The study also found that the LCD score, which considers overall diet quality and not just carb quantity, provided useful additional information for predicting blood sugar control.
Previous research has suggested that low-carbohydrate diets can help with blood sugar control in type 2 diabetes, but this study provides more specific guidance about which measurement methods actually work best. Most earlier studies focused on total carb grams or simple carb counting, but this research shows that thinking about carbs as a percentage of total calories is more predictive. This aligns with newer understanding that the proportion of macronutrients (carbs, protein, fat) matters for blood sugar management.
This study only looked at one point in time, so it can’t prove that changing carb intake will improve blood sugar—only that certain measurements are connected to blood sugar levels. The study included 238 people, which is good, but all participants had type 2 diabetes, so results may not apply to people without diabetes. The study didn’t track people over time to see if these recommendations actually work long-term. Additionally, the study didn’t account for other important factors like physical activity, stress, sleep, or medication use, which also affect blood sugar control.
The Bottom Line
If you have type 2 diabetes, consider working with a dietitian to keep carbohydrates at about 50-55% of your total daily calories rather than focusing only on carb grams. This approach appears to be more effective for blood sugar control. The Low Carbohydrate Diet scoring system may also be helpful. These recommendations have moderate confidence based on this research, but should be personalized to your individual needs and medical situation.
People with type 2 diabetes who are trying to improve their blood sugar control should pay attention to these findings. Healthcare providers managing diabetes patients may find this helpful for giving dietary advice. People without diabetes don’t need to apply these specific recommendations. Anyone on diabetes medication should talk to their doctor before making major diet changes, as medication doses may need adjustment.
Blood sugar improvements from dietary changes typically appear within 2-4 weeks, though some people see changes sooner. Longer-term benefits usually become clearer over 3-6 months of consistent dietary changes. Individual results vary based on starting point, medication use, and how strictly someone follows the recommendations.
Frequently Asked Questions
What’s the best way to measure carbs if I have type 2 diabetes?
Focus on carbohydrates as a percentage of your total daily calories rather than just counting grams. Research shows keeping carbs at 51.5% or less helps control blood sugar after meals, while 55.5% or less helps with fasting blood sugar.
How much of my daily calories should come from carbs if I have diabetes?
A 2026 study of 238 diabetic patients found that keeping carbohydrates at about 50-55% of total daily calories was most effective for blood sugar control. The exact percentage depends on whether you’re focusing on after-meal or fasting blood sugar.
Is counting carb grams still useful for managing type 2 diabetes?
While carb grams provide some information, research shows that measuring carbs as a percentage of total calories is more predictive of blood sugar control. Combining both approaches with a focus on carb percentage may be most helpful.
What is the Low Carbohydrate Diet score and should I use it?
The LCD score considers overall diet quality beyond just carb quantity. A 2026 study found it was the second-best predictor of blood sugar control, with scores above 23.5 for after-meal blood sugar being most effective. Ask your dietitian if it’s right for you.
How quickly will my blood sugar improve if I follow these carb recommendations?
Most people see blood sugar improvements within 2-4 weeks of consistent dietary changes, though some notice changes sooner. More significant long-term benefits typically appear over 3-6 months. Results vary based on individual factors and medication use.
Want to Apply This Research?
- Track your daily carbohydrate percentage (not just grams) by logging all meals and calculating what percentage of your total daily calories came from carbs. Aim to keep this at or below 51.5% for after-meal blood sugar control or 55.5% for fasting blood sugar control.
- Instead of just counting carb grams, shift your focus to calculating carb percentage of total calories. When planning meals, ask: ‘Are carbs making up more than half my calories today?’ This simple mental check can guide better choices throughout the day.
- Check your carb percentage weekly and track your blood sugar readings (if you monitor at home) to see if staying within the recommended ranges improves your numbers. Share this data with your healthcare provider at regular appointments to adjust your plan if needed.
This research provides information about carbohydrate measurement methods and their relationship to blood sugar levels in type 2 diabetes. It is not medical advice. If you have type 2 diabetes, consult your healthcare provider or registered dietitian before making significant dietary changes, especially if you take diabetes medications, as adjustments may be needed. Blood sugar management is individual and depends on many factors including medications, physical activity, stress, and overall health. This study was cross-sectional and cannot prove cause-and-effect relationships. Always work with your healthcare team to develop a personalized diabetes management plan.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.