Diabetes & transplantation - what does this mean for my diet?

Diabetes - what is it anyway?

In diabetes, the concentration of sugar (=glucose) in your blood increases. If your medical team suspects that you are diabetic, they will first test your blood sugar in a fasted state - i.e. after 8 to 10 hours without food. If it is significantly elevated, this indicates diabetes. The reasons for this can vary. Therefore, a distinction is made between type I and type II diabetes.

• Type I diabetes: The key to getting sugar from your blood into your cells is the hormone insulin. In type 1 diabetes, the insulin-producing cells of your pancreas are gradually destroyed until your body can no longer produce insulin itself. Mostly the reason for this is a malfunction of the defense system (=immune system), whereby the defense cells attack and destroy the insulin-producing cells (=beta cells). This is why type 1 diabetes is also classified as an autoimmune disease. If the key - insulin - for the cell door is missing, the sugar no longer enters the cells and remains in the blood. As a result, the blood sugar level increases.
• Type II diabetes: Here, the body's cells no longer respond as well to insulin. This is often due to the fact that the blood sugar - and thus also the insulin level - was previously too high too often. But hereditary factors also seem to play a role. In response to this, your cells react only slowly to the hormone insulin. This is also called insulin resistance. As a result, more sugar remains in the blood and your cells lack energy.

Diabetes & kidney transplantation - how are they related?

Worldwide, the number of people with diabetes is increasing. Statistics show that as many as one in eleven adults in the world is diabetic - that's around 425 million people. But how are diabetes and the health of your new kidney connected in the first place, and what are the things to pay special attention to after the transplant?

1. Diabetes and kidney function

If diabetes persists for several years, glucose is also deposited in your blood vessels. Your vessels become hard and inelastic and your blood flows less well through them. This leads to circulatory problems in your organs. The vessels in your legs, heart, brain and kidneys are particularly affected.

Diabetes can therefore damage the vessels in your kidneys over a long period of time, leading to kidney insufficiency. The most common cause of chronic kidney disease (CKD) is diabetes, and almost 50% of people on dialysis are diabetics. Therefore, your blood sugar levels and the function of your (new) kidney are closely related. Some studies even show that healthy blood glucose levels can positively influence the function and lifespan of your new kidney after transplantation.

2. Post-transplant Diabetes Mellitus (PDMT) after kidney transplantation.

Your blood glucose levels are of great importance after the transplant. This is especially important for diabetic patients. However, especially after transplantation, the likelihood of developing a new diabetes is also increased. One reason for this may be the effect of immunosuppressive drugs. Simply put, these drugs suppress the effect of your defense system (=immune system). Thus, these drugs make it easier for your new kidney to arrive in your body and protect it from rejection by your immune system.

However, these drugs also influence your blood sugar metabolism. In particular, the use of so-called corticosteroids (e.g. cortisone) stimulates the formation of new sugar molecules in your body and can thus increase your blood sugar. In the first 3 years after kidney transplant, up to 25% of people develop diabetes. This phenomenon is often called post-transplant diabetes mellitus (PDMT). But don't worry, often only temporarily elevated blood glucose levels show up and of course there are a number of tips and tricks to have a positive impact on your sugar metabolism. You can also learn how to recognize diabetes in general after kidney transplantation and which measures will help you to manage it in many other articles from the Mizu App.

Low-bacteria diet for diabetes after kidney transplantation

Whether you develop diabetes after transplantation or already had high blood glucose levels before transplantation, you know for sure that in addition to your medications, adjusting your weight and blood pressure, and getting enough exercise, diet plays an enormously important role in managing diabetes.

But what changes now when transplant and diabetes meet in combination? Many factors are similar - for others, you should pay specific attention to a few adjustments. This is especially true for the low-bacteria diet. This is important because your body can no longer defend itself so well against pathogens due to reduced activity of your immune system (=immunosuppression). By eating a low-germ diet, you protect your body from infections. How you combine the low-germ diet with the basics of diabetes nutrition and what else you should pay attention to, we want to show you with some examples in the following.

Carbohydrates

With diabetes...

...it is important to avoid carbohydrates with a high glycemic index, i.e., those such as white bread, French fries or sweets, in meals. The glycemic index is a measure used to determine the effect of a carbohydrate-containing food on blood sugar levels. The higher the value, the less suitable the food is for you.

In diabetes and transplantation...

...you should always use carbohydrates that do not raise your blood sugar as much - i.e. with a lower glycemic index. That means, for example, whole grain pasta rather than normal pasta.

For a low-bacteria diet, you should buy only fresh bread and rolls. You should be careful with rolls or bread that are sold in self-service departments or come pre-sliced. But usually fresh bread from the bakery tastes much better than the baked goods from the self-service counter in the supermarket. And if you're in a hurry, you can also use baked rolls. By heating them in the oven, they no longer pose a risk of infection for you.

Also, be careful with pastries containing cream, pudding or fruit, as errors in cooling can lead to additional exposure to germs and thus an increased risk of infection. Instead, feel free to use a freshly cooked compote that you can serve as a topping with your pastries. If you heat the compote strongly during preparation, the germs will be killed. Depending on the season, you can vary the type of fruit in your compote to create variety. In winter, for example, a compote of apples or pears tastes great. You can also add winter spices such as cinnamon or cloves to enhance the flavor. In summer, you can prepare a compote of berries, for example. Here, too, you don't have to worry about germs if you heat them up a lot.

Muesli mixtures with dried fruit or nuts should ideally be avoided. But just add a spoonful of home-cooked compote and you will see that it tastes much more refreshing than with dried fruit.

You can also eat freshly prepared cereals without any problems.

Dietary fiber

With diabetes...

...since you as a diabetic should rather rely on carbohydrates with a low glycemic index, a high-fiber diet is recommended. This can be achieved by eating whole grains, raw vegetables and legumes.

In diabetes and transplantation...

...fiber is also important for a healthy and wholesome diet. You should not do without it even after transplantation. Dietary fiber is mainly found in fruits, vegetables, whole grains, nuts, seeds or mushrooms.

Here, as always, caution is advised with regard to germs. Make sure to eat raw vegetables and fruits freshly washed and peeled. Thoroughly washed and cooked vegetables, fruits or legumes are also a good alternative (e.g. peas, beans, spinach, savoy cabbage, etc.). Frozen vegetables in particular should always be cooked. Salad from fresh food counters or a salad bar should rather be avoided. Nuts or seeds (e.g. walnuts, hazelnuts, linseeds) should only be eaten heated after transplantation, if at all.

The simplest solution is of course fruit with peels such as oranges, bananas or kiwis. Here, the peel can be removed quite easily. Only pay attention to high potassium values, if necessary.

Fat

In diabetes...

Trans fats are unsaturated fatty acids. They are formed when originally healthy vegetable oils are industrially processed or oil is heated very strongly over a long period of time, such as in a deep fryer. They are considered unhealthy because they can increase bad blood fats. When it comes to meat, you should rather opt for low-fat products. Fish, on the other hand, offers a good source of healthy omega-3 fatty acids.

With diabetes and transplantation...

...the rules remain basically the same. However, you should always cook or boil fish and meat before eating. Freshly prepared fish is best. Sushi, mussels, carpaccio, pickled herring and other raw fish are taboo. Smoked or pickled fish is also not a good idea.

Protein 

With diabetes...

...a high-protein diet is often recommended. Experts suggest that a diet high in protein but low in calories may be beneficial for people with type II diabetes.

In diabetes and transplantation...

...adequate protein intake is also important. In the first weeks after transplantation, up to 1.4 g of protein per kg of body weight per day is recommended, as you may lose more protein through your new kidney. In the long term, you should consume between 0.8 and 1.0 g protein per kg body weight per day. A lot of protein can be found in animal products, such as meat, fish or eggs. But also legumes such as lentils contain protein.

Meat is best cooked through or boiled and then consumed directly. Especially in the case of minced meat (e.g. goulash, ground meat), long storage should be avoided. In the case of poultry meat, great importance should be attached to kitchen hygiene. You can find out exactly how to do this in our other articles on nutrition after transplantation. Since you cannot estimate how high the hygiene standards are in restaurants or snack bars, you should only eat this type of meat after preparing it yourself.

For sausages, you should choose cooked cured meats (e.g. cooked ham, Kassler) or cooked and boiled sausages (e.g. Fleischwurst, Bierwurst, Lyoner). Do you really need to eat sausages or cold cuts? Then, as always, make sure that they are fresh and avoid products from the deli counter or breakfast buffet that may be contaminated with germs.

Energy supply

With diabetes...

...it is important to eat a calorie-conscious diet and often achieve controlled weight loss.

In diabetes and transplantation...

...a calorie target of 25 - 35 kcal per kg body weight per day usually applies. KDIGO recommends that if you are significantly overweight, i.e., have a BMI greater than 30, reduce your calculated daily goal by ****500 to 1000 kcal. However, if your treatment team recommends weight reduction, you can and should always ask for specific instructions here.

Phosphorus

With diabetes...

...you can follow the normal amount and usual dietary recommendation of about 2000 mg daily.

In case of diabetes and transplantation...

...you should adjust your phosphate intake to your blood values. Especially in the period shortly after transplantation, your phosphate levels may fluctuate. If your phosphate levels are too high, you should follow a low-phosphate diet to avoid possible secondary diseases. However, individual factors must be taken into account, which is why you should definitely talk to your nephrologist about this topic.

Table salt

With diabetes...

...there are no differences to the usual recommended low-salt diet of a maximum of 6 g of table salt daily.

In diabetes and transplantation...

...it is important to keep an eye on your daily salt consumption. Specifically, you should aim for a maximum of 5 g of table salt daily. You can also find more detailed information and practical tips on the low-salt diet in the Mizu app.

General dietary styles

With diabetes...

...there are different eating styles that have different advantages and disadvantages. Dietitians can give you the best overview here.

In diabetes and transplantation...

...the Mediterranean diet is often recommended. Some studies show that the Mediterranean diet may support the function of your new kidney. In general, the only recommendation at this time is to watch your protein and calorie intake while controlling your blood glucose, phosphate and potassium levels. Your HbA1c (long-term blood glucose) value offers you a good indication for controlling your blood glucose values.

One more thing!

So you see, with a few tips and tricks you can reconcile nutrition for diabetes and transplantation. Adjusting your diet is incredibly important and essential for avoiding further secondary diseases or infections. This may be a little challenging, especially at first. Always talk openly with your medical team about practical tools, guides & tricks! Regular check-ups are also helpful in order to be able to react to changes in your kidney and/or blood sugar levels at an early stage.