Understanding Carbohydrates and Blood Sugars

Carbohydrates are one of the three essential macronutrients, alongside fats and proteins, that your body uses for energy. For individuals with diabetes, understanding how carbohydrates affect blood sugar levels is crucial. Once you eat carbs, your body breaks them down into glucose, the primary fuel for your cells. However, with diabetes, the body’s ability to use glucose properly is impaired, making carb awareness essential for glucose management.

Foods That Contain Carbohydrates

To effectively manage your blood sugar, it’s important to recognize which foods contain significant amounts of carbohydrates. Common sources include:

  • Grains: Bread, pasta, cereals, rice, tortillas
  • Fruits: Apples, bananas, grapes, and all fruit juices
  • Vegetables: Especially starchy ones like potatoes, corn, peas
  • Root crops: Sweet potatoes, yams, carrots
  • Legumes: Lentils, beans, chickpeas
  • Dairy: Milk, yogurt (except most cheeses)
  • Sweets: Candy, cakes, cookies, ice cream
  • Beverages: Regular soda, beer, wine, some liquors
  • Sugars ending in “-ose”: Sucrose, fructose, maltose

Even some healthy foods contain carbs. Knowing their carb content helps you match your medication or insulin dose to your meal.

Carb Counting for Diabetes

Carb counting helps people with diabetes regulate their blood sugar, especially those using insulin. One common method is counting grams of carbohydrate per meal:

  • 1 slice of bread ≈ 15g carbs
  • 1 small apple ≈ 15g carbs
  • ½ cup of cooked pasta ≈ 20g carbs

Most people with diabetes aim for 45–60 grams of carbs per meal, but needs vary depending on your body size, activity level, and type of insulin or medication. Learn more from the American Diabetes Association’s guide to carb counting.

Complex vs Simple Carbohydrates

Carbohydrates are not all created equal. They are generally classified into two types:

Complex Carbohydrates

These include whole grains, legumes, vegetables, and some fruits. They contain fiber, vitamins, and minerals and are digested more slowly, causing gradual rises in blood sugar. Examples include:

  • Brown rice
  • Quinoa
  • Lentils
  • Oats
  • Broccoli
  • Sweet potatoes

Complex carbs are lower on the glycemic index (GI), which ranks how quickly foods raise blood sugar. A lower GI means better glucose stability.

Simple Carbohydrates

These are found in candy, soda, white bread, pastries, and most processed foods. They cause rapid spikes in blood sugar and provide few nutrients. Frequent consumption can lead to insulin resistance and worsen diabetes control.

Occasional small amounts are okay, especially if balanced with a healthy meal and proper insulin coverage. But nutrient-dense carbs should form the foundation of your carb intake.

The Glycemic Index and Glycemic Load

The Glycemic Index (GI) ranks carbs by how quickly they raise blood sugar. Foods with a high GI (70 or more) raise glucose faster than those with a low GI (55 or less). But the Glycemic Load (GL) is even more useful because it also considers portion size.

  • Low GI + low portion size = low blood sugar impact
  • High GI + large portion = blood sugar spike

Low-GI eating has been shown in studies to improve HbA1c in people with both type 1 and type 2 diabetes (Jenkins et al., 2008).

Final Thoughts: Choose Carbs Wisely

Carbohydrates are a necessary part of a balanced diet, but the type and quantity are important. Choose complex, fiber-rich carbs most often, and limit sugary, refined foods. For those using insulin, accurate carb counting helps keep blood glucose levels stable and reduces the risk of lows and highs.

Discuss your ideal carb intake with your diabetes care team, or consider consulting a registered dietitian specializing in diabetes care. Tools like continuous glucose monitors (CGMs), food tracking apps, and meal plans can make managing carbs easier and more effective.

Need help with your insulin-to-carb ratio or glucose spikes after meals? Check out our other tools and articles designed to help you succeed.