Low Carbohydrate Diets in Type 2 Diabetes

Type 2 Diabetes and Carbohydrates

Carbohydrates include starches, such as those found in bread, potatoes and rice; as well as sugars, such as those found in sugary drinks, cakes, biscuits, pastries and ice cream. They are one of the basic food groups and are used by our body as a source of fuel for the brain and energy for muscles. 

When carbohydrates, or ‘carbs’, are digested, they are broken down into glucose and absorbed through our gut into the bloodstream. It doesn’t matter whether it is a glass of fruit juice, organic wholemeal bread, rice or chocolate- they all can cause blood sugars (or glucose) to rise. The pancreas responds by producing insulin to help transport the glucose from the blood into the cells to be used as energy.

If the glucose is not immediately needed for energy, the body stores it as glycogen in the liver. Once glycogen stores are full, ingested carbohydrates are stored as fat.

In people with type 2 diabetes, the body’s cells are resistant to insulin so blood sugar remains high. To compensate, the pancreas produces more insulin, attempting to bring blood sugar down. Over time, the pancreas loses its ability to produce enough insulin. As a result, some of the glucose stays in the blood causing high blood glucose levels.

Although carbohydrates are the major source of energy for the body, proteins and fats can also be a source of energy. Fat, the main source of energy in a low carbohydrate diet,  provides energy in a very gradual way that can help to keep you feeling full for a number of hours.


Low Carbohydrate Diets in Type 2 Diabetes by Dr Mohgah Elsheikh

Low Carbohydrate Diets in Type 2 Diabetes by Dr Mohgah Elsheikh


Can Low Carbohydrate Diets Help Manage Type 2 Diabetes?

A low carbohydrate diet involves drastically reducing carbohydrate intake and replacing it with healthy fats. Reducing sugar and starchy carbohydrate consumption will reduce blood sugar (glucose) levels. It can also help reduce the fat in the liver and around the pancreas, making them work more efficiently.

Research has shown that people with type 2 diabetes who follow a low carb diet tend to experience long-term improvements (up to 12 months) in blood sugar control. The lower intake of carbohydrates in the diet can help to eliminate large spikes in blood sugar and improve Hba1c. Many people with type 2 diabetes who follow a low carb diet also have marked reduction in medication needs, and in some cases, medication may be stopped completely. In addition, low-carb diets may improve blood pressure, high-density lipoprotein (HDL) ‘good’ cholesterol and triglyceride values

Although many people with type 2 diabetes mellitus lose weight and have more stable blood sugars on a low carbohydrate diet it is not for everybody. No single diet is suitable for everyone as individual metabolism, genes, lifestyles and personal preferences differ. 


What is the Optimal Carbohydrate Intake for Patients with Type 2  Diabetes?

Carbohydrate intake below 130g per day has been shown to be effective at improving blood sugar control. The optimal amount of carbohydrates varies by the individual since everyone has a unique response to carbohydrates.

Rather than eliminating all carbohydrates, a healthy low-carb diet should include nutrient-dense, high-fibre carb sources like vegetables, berries, nuts and seeds. However, starchy foods such as bread, rice, pasta and potatoes are largely restricted. 

When carbohydrate intake is reduced less calories are consumed. When eating fat, it is important to select healthy unsaturated fats for example avocadoes, olive oil, oily fish and nuts, to help protect against heart disease.


Which Carbs Raise Blood Sugar Levels?

Carbohydrates in plant foods are made up of a combination of starch, sugar and fibre. Of these, only the starch and sugar components raise blood sugar, while fibre does not. Fibre does not break down into glucose and therefore does not raise blood sugar levels.  

The value of carbohydrates we need to look at, then, excludes fibres and are called, ‘is net carbs’. For example,  a medium sweet potato has about 21 grams of carbohydrate and about 3 grams of fibre so its net-carb amount would be about 18gram whereas one cup of cauliflower contains 5gram of carbs, 3 of which are fibre. Therefore, its net carb content is 2 gram.


Practical considerations


  • Ensure good nutrition


The overall goal is to eat less processed foods. Eat fresh, healthy Mediterranean-style foods. In addition to meat, poultry and seafood, include dairy foods, nuts, healthy fats and fresh vegetables.

Include a range of high fibre foods such as vegetables, legumes, low carb fruits and whole grains to help maintain a balance of healthy gut bacteria. Diets rich in fibre from a variety of different sources, and pulses, have been shown to be protective against bowel cancer and heart disease.

Include mostly healthy unsaturated fats such as those found in avocado, olive oil and nuts.

Avoid high-energy, high carb processed foods and drinks, such as sugary drinks (including fresh fruit juice), chips, cakes, biscuits, pastries and lollies.


  • Watch for possible side effects


There is a period of adaptation when switching to a low carb way of eating, and this is usually around two weeks. During this time, you may experience side effects such as:

  • constipation
  • leg cramps
  • loss of energy
  • mental fogginess
  • frequent urination
  • headaches
  • bad breath

These symptoms soon pass as the body adapts and can often be avoided by staying hydrated and getting enough electrolytes. People usually experience no long-term health problems. 



If you are using insulin or certain diabetes medications reducing your intake of carbohydrates can increase the risk of hypoglycaemia (very low blood glucose levels). 

Before you start a low carb plan, it is important that you monitor your blood glucose levels and consult your doctor/diabetes team so changes can be made to your medication. 


  • Beware of hypotension


You may feel dizzy or light-headed in the first few days, or even weeks, of a low-carb diet as you adapt to this new way of eating.  On a low-carb diet, your body sheds excess water and you will notice you will urinate more frequently. You will also lose some minerals such as sodium. This is why excess bloating improves within a few days of low-carb eating.  However, this can also result in dehydration and loss of electrolytes causing low blood pressure and muscle cramps. Increasing your intake of water and salt will help reduce the symptoms. If you have high blood pressure then we will monitor your blood pressure in the first few weeks of the diet  and your blood pressure medications may need to be reduced.


Getting started on low-carbs – As easy as A-B-C

A – Adequate protein, B – Brightly coloured vegetables, C – Careful carbs


Foods to Eat and Foods to Avoid

Focus on eating high-quality low carb foods as close to their original form as possible (not processed!) It is also important to pay attention to your body’s hunger and fullness cues, regardless of what you are eating.


Low carbohydrate foods to eat

The green light category contains foods that are unrefined whole foods. You can eat the following low-carb foods until you’re full, and you should make sure to get enough protein at each meal.

  • Meat, poultry and seafood: enjoy good quality meat and fish such as chicken, beef, lamb, duck, salmon, tuna, mackerel and shellfish. 
  • Eggs: cooked any way you like – scrambled, omelette, poached or boiled
  • Non-starchy vegetables. Enjoy leafy greens, spinach, lettuce, mushrooms, cauliflower, broccoli, courgettes, cabbage. Asparagus, eggplant, olives,  cucumber, peppers and tomatoes
  • Olives and avocado


Foods to eat in moderation

The yellow light category contains foods that you can include in small to medium quantities because they have a higher carbohydrate or calorie content.

  • Berries (Strawberry, Raspberry, Blueberry, blackberry): 1 cup or less.
  • Other fruit: a small apple, orange or pear
  • Plain, Greek yoghurt: 1 cup or less.
  • Eat cheese in moderation–it is a very “calorific mixture of fat and protein 
  • Cottage cheese: 1/2 cup or less.
  • Nuts and seeds and nut butter (almonds, walnuts, pecans, hazelnuts, macadamia, brazil nuts, pumpkin seeds, sunflower seeds and macadamias):  30–60 grams. Beware of cashews as they have a high carb content
  • Flaxseeds or chia seeds: 2 tablespoons.
  • Dark chocolate (at least 85% cocoa): 30 grams or less.
  • Starchy vegetables (e.g., potatoes, peas, corn, winter squash)  or root vegetables (carrots, parsnips): 1 cup or less.
  • Wholegrains (brown or whole grain rice and pasta, rolled oats and whole-grain bread). Limit the portion size – they are not essential.
  • Beans, legumes and lentils: these contain both protein and carbohydrate so only eat in small quantities


Foods to avoid

The red light category contains the foods that we recommend minimising or and reducing as much as possible. These foods are high in carbohydrates and can significantly raise blood sugar levels in people with diabetes:

  • Sugar: all forms such as table sugar, honey, dried fruit, maple syrup,  agave and fruit syrups
  • Puddings, desserts, ice-cream, biscuits, cakes and pastries
  • Refined grains including white rice, pasta, noodles, bread and most breakfast cereals. Use cauliflower rice, courgette or carrot strips rather than spaghetti. Choose Bulgur wheat or Quinoa instead of Rice
  • Sweet tropical fruits such as mango, pineapple, grapes, dates and bananas are full of sugar and can set off carbohydrate cravings. 
  • Sugary drinks – avoid all drinks with sugar including fresh juices, smoothies, flavoured milks, fizzy and energy drinks, sweetened tea (including Karak tea) and coffee drinks. 
  • Unhealthy fatty foods such as batter, crisps, chips and fries, parathas, pastries and samosas. 
  • Seed oils – avoid seed oils because they are ultra-processed, easily oxidised and promote inflammation. Avoid canola oil, sunflower oil and margarine.  Avoid fried foods.

What to drink

  • Drink still or sparkling water. Put a slice of lemon or lime, mint leaves or a strawberry in the water if you like.
  • Drink herbal teas
  • Drink tea, coffee. Do not add sugar to your tea or coffee. Avoid Karak tea, cappuccinos and lattes which are full of sugar. Feel free to add a little milk but please note that 100ml milk has the equivalent of 1 teaspoon of sugar.
  • Sugary fizzy drinks should not be consumed. Drinking one fizzy drink a day is estimated to add 6.75kg  in weight per year to the average person.
  • Avoid fruit juice – did you know a 200ml glass of fresh orange juice has the equivalent of 8 spoonfuls of sugar! 
  • Artificial sweeteners are often used to sweeten diet drinks and other diet products. Some of them can actually raise blood sugar levels in people with diabetes. Moreover, recent studies show that artificial sweeteners may actually reduce the chances of weight loss.


Tips and guidance

  • Eat only when hungry and stop when you are full
  • Avoid sugar and flour-based foods
  • Eat nutrient-dense food: good-quality meat or fish, non-starchy vegetables, full-fat dairy, nuts and seeds.
  • When beginning, read ALL food labels. You will soon learn what to buy and what to avoid. 
  • Choose food that has been processed as little as possible. Avoid take-away and prepackaged foods.
  • Beware of low-fat foods–they often have sugar or sweeteners added to make them palatable.
  • Do not drink your calories. Fizzy drinks, fruit juice, flavoured milks and smoothies are packed with sugar. Drinking a glass of orange juice isn’t the same as the goodness from six oranges – it’s the same as drinking the sugar from six oranges.
  • Eat enough healthy fat to keep you full until the next meal.
  • Enjoy lower-carbohydrate fruit and berries in limited quantities.
  • Try not to rely on sweeteners in the long-term.  Diet drinks can help you get off the sugary soda, but eventually, you should try to give these up altogether.
  • When eating out, avoid breaded, battered or crumbed dishes, pasta, rice and anything with sweet sauces. Decline the bread basket. 
  • You may experience tiredness and a headache in the first few days – drink plenty of water to stay hydrated.
  • Be organised, plan your meals a few days at a time and stock your pantry and fridge.