Key takeaways

• There is no single “diabetes diet”. 

• The key to eating for good blood glucose control is to control carbohydrate intake, ensure an adequate fiber intake, choose whole food options as often as possible, and limit sugar and saturated fat intake. 

• Meal composition also affects blood glucose control. 

The impact of diet on diabetes control

Our meals directly impact our blood glucose levels. 

When we eat, the food is broken down and some of it is converted to glucose, causing our blood glucose levels to increase. Blood glucose is an important source of energy for our bodies. When our blood glucose levels increase, our pancreas (an organ in the body) produces insulin. Insulin acts as a key to our body’s cells and allows glucose to move from the bloodstream into the cells for storage. 

In type 2 diabetes, insulin resistance occurs, where the body is unable to use insulin effectively, causing excess blood glucose to stay in the blood. Being overweight and having excess body fat also increases insulin resistance. Persistently high blood glucose levels can cause damage to certain organs (e.g. heart, kidney, eyes). 

Through various diet strategies, we can influence our weight and blood glucose response after meals, and thus improve diabetes control. 

Is there a “diabetes diet”?

There are many diets that have shown to be helpful for improving diabetes control. 

Ketogenic / low carbohydrate diets

Studies have shown that the ketogenic or low carbohydrate diet can be effective at improving blood glucose control as carbohydrate intake directly affects blood glucose levels. However this can result in ketosis (where the body switches to burning fat instead of carbohydrates for energy) and is not safe for some groups of people, including women who are pregnant or breastfeeding or people with kidney disease. People taking SGLT-2 inhibitors should also avoid ketogenic or very low carbohydrate diets due to the increased risk of diabetic ketoacidosis. Additionally, the health impact of following a low carbohydrate diet in the long term is not well-established and a high fat intake, which is typical of a ketogenic diet, could increase blood cholesterol levels and risk of cardiovascular disease. 

Mediterranean diet

There is research showing that the Mediterranean diet, which emphasizes vegetables, fruits, legumes, wholegrains, fish, nuts, and healthy fats, is able to reduce body fat and consequently improve glycemic control. In addition, when compared to other calorie-restricted diets, a greater improvement in insulin resistance has been seen with the Mediterranean diet in people with obesity. This suggests that on top of getting into a caloric deficit, the composition of the diet also plays a role in improving diabetes control. 

Other diets

There is also emerging evidence that a plant-based diet, which is likely to be higher in carbohydrate albeit also higher in fibre, improves diabetes control.  

Other research showed that the type of fat (saturated versus unsaturated) and protein (animal versus plant) also play a role in blood glucose control. 

As such, there is not one “diabetes diet”. Instead, meal planning should be individualized based on current eating patterns, preferences, and health goals. A variety of dietary approaches can help with managing type 2 diabetes, as long as meals are largely comprised of whole, minimally processed foods. Intake of sugar and saturated fat should also be limited.

Key diet principles for managing blood glucose levels 

The key principles for a good diet for diabetes include:

1. Moderate carbohydrate intake.

2. Choose complex carbohydrates over refined carbohydrates.

3. Consume adequate amounts of fiber.

4. Choose whole foods.

5. Pair carbohydrates with protein, fiber, and unsaturated fat.

6. Consume fibre, protein and/or fats before carbohydrates.

7. Limit saturated fat.

Moderate carbohydrate intake 

Dietary carbohydrates are broken down into glucose and have the biggest impact on blood glucose levels – consuming a bigger carbohydrate portion results in higher blood glucose levels after a meal compared to consuming a smaller carbohydrate portion. Controlling carbohydrate portions at each meal, therefore, is a key strategy in blood glucose control. 

A good gauge is to fill only ¼ of your plate at each meal with a carbohydrate-rich food (e.g. rice, noodles, bread, pasta, starchy vegetables).  

Choose complex carbohydrate options instead of refined carbohydrate options as much as possible

The type of carbohydrate we consume also affects blood glucose response. 

Refined carbohydrate options are broken down easily and tend to cause bigger blood glucose swings which may promote excessive weight gain due to increased hunger and decreased satiety. They include options such as white rice/bread, dim sum, pastries, and sweetened foods and beverages. Research shows that refined carbohydrate options stimulate higher insulin production, which results in increased glucose uptake into the cells. This resulting drop in blood glucose levels could be responsible for hunger and overeating. Higher insulin levels also inhibit the breakdown of stored fat. 

On the other hand, complex carbohydrate options are higher in fiber, causing it to be broken down more slowly, resulting in a lower and more gradual rise in blood glucose levels after the meal. 

Choose unprocessed, complex carbohydrate options when you can. For example, brown rice instead of white rice, wholegrain bread instead of white bread, chapati instead of prata. Other complex carbohydrate options include corn, sweet potato, quinoa, and lentils. 

Adequate fiber intake 

Fiber decreases inflammation, improves gut health, and delays gastric emptying, causing blood glucose levels to rise more gradually after a meal. Furthermore, fermentation of dietary fiber in the gut produces short chain fatty acids which help regulate blood glucose, improve insulin sensitivity and increase satiety. 

Wholegrains, vegetables, fruits, nuts, and seeds are good sources of fiber. Including a wide variety of these foods in your meals is a good way to obtain different vitamins and minerals and is beneficial for gut health. 

Choose whole foods 

When foods are processed, important nutrients like fibre, vitamins and minerals are often lost. In addition, saturated fat and sugar, both of which have a negative impact on blood glucose control, are often added. Sodium is also commonly added which can affect blood pressure.

One study found that those with lower-quality diets, characterised by an inadequate balance of each food group (carbohydrates, protein, vegetables and fruit), an inadequate intake of important nutrients, and an excessive intake of certain nutrients (e.g. saturated fat, sugar, salt), had nearly 3 times the odds of having poorer blood glucose control. 

Choosing whole, unprocessed options (e.g. fresh fruit and vegetables, wholegrains, poultry, meat, fish) is the most effective way of obtaining the nutrients you need without consuming excess fat, sugar and salt. 

Pairing

Research has shown that meal composition also affects blood glucose control. Eating carbohydrates together with fiber, protein, and fat can slow gastric emptying and reduce blood glucose increase after the meal. 

After filling ¼ of your plate with carbohydrates, fill another ¼ of the plate with a lean protein option and the other ½ with non-starchy vegetables for a well-balanced meal. 

Try to avoid dishes high in saturated fat (e.g. deep-fried options, curries, fatty meats) as saturated fat promotes fat storage and may lead to weight gain in the long term.

Sequencing 

This is probably one of the simplest strategies to improve blood glucose control. Research has found that consuming protein and/or fat before carbohydrates promotes the secretion of glucagon-like peptide-1 (GLP-1) which regulates insulin secretion and slows gastric emptying, thus helping to keep blood glucose levels more stable after meals. GLP-1 also suppresses appetite and can help with managing weight. Consuming fiber before carbohydrates also reduces blood glucose increase after meals. 

When having your meals, start with a few mouthfuls of vegetables and protein before the carbohydrates for better blood glucose control. 

Limit saturated fat 

High-fat diets, especially the intake of saturated fat, contribute to insulin resistance. It can also worsen blood cholesterol levels. Saturated fat is found in fried foods, fatty cuts of meat, processed meats, pastries, and creamy dishes.

On the other hand, there is evidence showing that a moderate consumption of unsaturated fat (e.g. extra virgin olive oil) can lower fasting blood glucose levels and HbA1c. Unsaturated fat can decrease inflammation and improve insulin sensitivity. Good sources of unsaturated fat include olive oil, canola/sunflower oil, oily fishes (e.g. salmon, tuna, sardine), avocado, nuts and nut butters. 

Total fat intake should still be controlled since a high total fat intake increases insulin resistance, even if unsaturated fats are consumed. 

How do I know which diet works for me? 

Instead of having to adopt a certain meal plan or diet, you can simply incorporate the key healthy eating principles above into your diet. This allows you more liberty with your food choices which can help with sustaining these new diet habits in the long term. 

There are however a few things worth considering.  

Achieving good blood glucose control (and other health markers) 

When embarking on any new diet, it is worthwhile seeing how your blood glucose levels respond. Different people will have different blood glucose responses so understanding your own body’s response is the best way to figure out which diet or meal strategies work best for you. You can monitor your blood glucose levels using a glucometer or continuous glucose monitor. 

Other health markers (e.g. blood cholesterol levels) should also be monitored. Some studies found that while people experienced weight loss and improved blood glucose control on a low carbohydrate diet, they also experienced an increase in blood cholesterol levels. 

As such, understanding how the new eating pattern is affecting your health markers is crucial to finding the diet that is best suited to you.  

Adequacy 

Getting all the nutrients you need is also key to long term good health. In our attempt to follow a new diet, sometimes we may miss out on certain essential nutrients. Ensure you are including a good portion of each food group every day and choosing a variety of foods (especially fruits and vegetables). 

Sustainability 

Finally and perhaps most importantly, ask yourself if you are comfortable and able to sustain this way of eating. This allows you to maintain the health benefits in the long term. 

Getting support

It can be difficult to know where to start and how to figure out if a diet is working for you. The NOVI Magnum program, which includes one-to-one consultations and support from an experienced dietitian can help make your journey simpler.