Type 1 diabetes – how to control your blood sugar with fewer carbs

Type 1 diabetes – previously called “juvenile onset diabetes” – results when the body is no longer able to produce enough of the blood sugar-lowering hormone insulin that it needs. Fore some reason (usually autoimmunity) the majority of the insulin-producing beta cells in the pancreas has died.

Type 1 diabetes is treated with injections of the insulin that the body lacks.

The more carbohydrates you eat the greater doses of insulin are needed. This usually makes the blood sugar more difficult to regulate, with higher average blood sugar levels. Many people therefore experience that a reduced amount of carbohydrates in the diet makes it easier to keep blood sugar stable and at normal levels.

The effect of fewer carbohydrates

Blood sugar before and after starting a low-carbohydrate diet

Blood sugar before and after starting a low-carbohydrate diet

Figure above showing blood sugar readings during ten days before and after starting a low-carbohydrate diet. Data from this study.

Note especially how much more stable blood sugar becomes. Before the change there are large spikes from carbohydrate-rich food, and large drops in blood sugar from corresponding amounts of insulin. Eating instead fewer carbohydrates and taking less insulin will logically enough produce much smaller fluctuations. It thereby becomes easier to maintain a more normal blood sugar level without risking hypoglycemia (low blood sugar).

Success stories

  • Type 1 diabetes and LCHF – a great combination
  • "Overall, I now have a completely new life"
  • "I still have 30 pounds to lose, but I've already won"
All type 1 diabetes success stories


Overweight diabetics (both type 1 and type 2) will as a rule lose weight on a low-carbohydrate diet.



But what happens to blood lipids when you eat fewer carbohydrates, and a higher proportion of fat? The fact is that recent studies (contrary to what was previously believed) show clearly improved cholesterol numbers.

Blood pressure

Blood pressure also often improves on a low-carbohydrate diet, which is partly, but probably not completely, explained by the weight loss.

I have heard of many people who have had to reduce or stop using blood pressure medications, when their blood pressure had dropped too low. A common symptom is then dizziness and a feeling of weakness.



With insulin-treated diabetes it’s important to monitor your blood sugar closely initially when starting an LCHF diet! A diet including few carbohydrates usually causes a greatly reduced need for insulin. It’s then important to adjust (lower) the doses sufficiently to prevent blood sugar from dropping too low. This should, if possible, be done with the support of your physician or diabetes nurse, especially if you have limited experience of insulin adjustment yourself. 

You also need to be diligent about closely checking your blood sugar in the event of an acute illness, please see below. 

Insulin for people with type 1 diabetes


The doses of insulin need to be reduced significantly on a low-carbohydrate diet. As a starting point, a reduction of 50% may be appropriate when on a strict LCHF diet (compared to eating plenty of carbohydrates). However, this varies with the individual and it’s not possible to predict how large a reduction is needed. There’s only one reliable way: check your blood sugar often when changing your diet and adjust doses accordingly.

If you feel uncertain, make a gradual transition with a gradually reduced amount of carbohydrates in the diet over a few days or more.

The result (after adjusted dosing) will usually be significantly more stable blood sugar, with a decreased risk of hypoglycemia, in addition to other potential benefits on weight and health from lower insulin doses.

To be able to manage entirely without insulin injections in the long run will, in principle, not be possible regardless of how few carbohydrates you eat. However, some people may in the best case maintain well-regulated blood sugar with only basal insulin when on a strict LCHF diet. Mealtime insulin will then be something that’s only used if one makes an exception and eats more carbohydrates.

If blood sugar drops too low

Immediately eat something carbohydrate-rich, such as a fruit or a sandwich. A glass of juice or glucose tablets may also work well. They raise blood sugar. If your blood sugar drops too low you should strongly consider reducing your medication. If you need help doing this contact your doctor.

Acute illness and ketoacidosis

Note also that the need for insulin – regardless of which foods you eat – increases with acute illness. It’s not uncommon with dangerous ketoacidosis (life threatening condition caused by severe insulin deficiency) in connection with, for example, stomach illness during which you don’t eat and therefore may forget to take your insulin.

The same applies if you eat an LCHF diet. The insulin-requirement may increase with illness. If you normally take low doses it is of course extra important not to miss this increased need. Don’t forget this. Missing the increased need for insulin when ill, is likely the greatest risk with low-carbohydrate diets and adjusted low insulin doses.

Common questions and answers

I HAVE TO eat carbohydrates regularly or I’ll suffer a blood sugar drop.

Yes, IF you take the same doses of insulin you take today, then you probably have to consume plenty of carbohydrates. But if you adjust the insulin doses according to your needs you don’t have to do this.

The question is: should you allow insulin to control your life, or would you be willing to adjust insulin doses to fit the life you lead? In the latter case an LCHF diet may work great, as it has for many type 1 diabetics who have tried it.

As noted above the insulin doses usually need to be lowered significantly. It’s not uncommon that doses need to be halved.

Don’t fat-laden sauces, lots of cheese and butter mean death for me as a type 1 diabetic? For diabetics, the risk of getting cardiovascular disease is increased, and a diet based on large amounts of fat would be like signing up for a future heart attack?

This is an old theory, that has been proven incorrect. Natural fats in food don’t cause heart disease, whether you are a type 1 diabetic, or not.

The problem with type 1 diabetes is exclusively a deficiency in insulin production, which makes it difficult to control blood sugar. High blood glucose levels over a long period of time is what then causes dreadful complications in the long run: heart disease, blindness, dialysis due to failing kidneys, amputations.

If you, with the help of a low-carbohydrate diet and adjusted insulin doses, normalize your blood sugar your body will work just as well as any healthy person’s. If you are able to maintain this the risk of long-term complications will likely be zero.

More on diabetes

Diabetes – normalize your blood sugar

Low carb for beginners

All blog posts on diabetes