Diabetes: Kidney Damage Reversed

A low carbohydrate diet may be appropriate to avoid the risk of kidney failure to already failing kidneys according to Swedish researchers.

An obese patient with type 2 diabetes whose diet was changed from the recommended high-carbohydrate, low-fat type to a low-carbohydrate diet showed a significant reduction in bodyweight, improved glycemic control and a reversal of a six year long decline of renal (kidney) function.

The reversal of the kidney function was likely caused by both improved glycemic control and elimination of the patient’s obesity.

Insulin treatment in type 2 diabetes patients usually leads to weight increase which may cause further damage to the kidney.

Although other unknown metabolic mechanisms cannot be excluded, it is likely that the obesity caused by the combination of high-carbohydrate diet and insulin in this case contributed to the patient’s deteriorating kidney function.

Metabolic control in type 2 diabetes is difficult because the recommended low-fat diet with its high content of carbohydrates usually leads to a vicious cycle:

  • High blood sugar levels caused by the high-carbohydrate diet necessitates the use of insulin.
  • Efforts to normalise the blood glucose with insulin leads to increase of appetite and bodyweight.
  • The rise of bodyweight exposes diabetes patients to the risk of obesity-associated kidney failure.

A low-carbohydrate diet, however, is a potent anti-high blood sugar remedy and may at the same time lead to weight loss.

The patient is a 60-year old man who was diagnosed with type 2 diabetes in 1989 and had a family history of overweight and diabetes. Traditional dietary counselling for weight loss usually resulted in a short-term loss of a few kg, but the bodyweight soon increased again.

In January 2004 his diet was changed radically by reducing dietary carbohydrates to 80–90 g per day, consisting only of vegetables and small amounts of hard bread (crisp bread). Potatoes, bread, pasta, rice and cereals were excluded, and the caloric requirements were covered by protein and fat.

To ease the transition the patient was supplied with a number of meal recipes suggesting a caloric restriction to about 1800 calories per day. The proportions in the recipes consisted of 20% carbohydrates, 50% fat, 30% protein.

Less than two weeks later the patient discontinued his insulin treatment and 6 months later his bodyweight had decreased by 19 kg.

Hemoglobin A1C had dropped to 6.5 % after 3 months. Hemoglobin A1C is tested to monitor the long-term control of diabetes and is increased in the red blood cells of persons with poorly controlled diabetes. From this test clinicians can estimate the average blood glucose level during the preceding two to four months. The target for most people is below 7.

The steady rise in his blood levels of creatinine stopped. When kidneys are damaged the amount of creatinine in your blood goes up. The creatinine has since, for two-and-a-half years, been stable. When insulin was discontinued rosiglitazone was prescribed.

Only after his weight loss of 19 kg, on the low carb diet, and an HbA1c reduction from a mean of about 8.5 % to 6.5 % was the steady decline of the kidney function reversed.

Two case reports have described the partially resolving and stabilisation of dialysis-requiring kidney failure after weight loss following bariatric surgery.

Retinopathy had been diagnosed in the patient in the mid-90s and in 2003 he developed proliferative retinopathy. In proliferative retinopathy new blood vessels start to grown within the eye. They are fragile and can bleed (hemorrhage), which may cause vision loss and retinal scarring.

As of late 2005 there was no sign of proliferative disease in the patient’s retinopathy.

Even though other unknown metabolic pathways and mechanisms may have been involved, it is still unlikely that this patient would have avoided dialysis if his diet had not been changed. This is suggestive of a causal relationship between the diet and the course of the patient’s kidney disease

A low-carbohydrate diet with self-regulated food intake has been shown to be superior to the traditional calorie-restricted, low-fat, high-carbohydrate diet for weight loss in five randomised controlled studies (as at June 2006).

The primary effect is caused by a lowering of appetite and a caloric intake reduced to the appropriate level for the patient’s height.

The protein content of a diet may be a concern, but the actual size of the effect of protein restriction is modest.

It is also a misconception that a low-carbohydrate diet automatically is high in protein.

This misconception may be a barrier for the use of a low-carbohydrate diet which is a highly effective tool in the management of type 2 diabetes.

Such a diet can be modified so it suits the patient’s needs i.e. the energy from carbohydrates can be replaced by energy from dietary fat and not necessarily from protein.

The patient here was given a number of meal recipes at start. The aim was to give him the means to learn how to use this new dietary tool, which in essence leads to a completely different mind-set regarding diet.

He was then recommended to consume about 70–90 g low-starch carbohydrates per day and to eat more fat.

The patient is today still keeping the carbohydrates at the recommended level. He eats more fat and probably about 80–90 g of protein per day.

A motivating factor, in addition to being able to see that the kidney function has stabilized, was probably the increased feeling of well-being that followed very soon after the dietary change.

Within 1–2 weeks of the dietary change – before any significant weight reduction had occurred – poor sleep and chronic fatigue was exchanged for a sound sleep pattern and increased vitality.

This effect soon allowed the patient to again involve himself wholly in the running of his company. The reversal of the tiredness seen with chronic hyperglycemia may have been the cause.

It may be that reversal of carbohydrate-induced memory impairment in type 2 diabetes played a role in restoring the patient’s alertness and self-confidence.

In adults with type 2 diabetes, poorer glycemic control is associated with lower performance on tests of declarative memory. Acute ingestion of high glycemic index carbohydrate foods further contributes to the underlying memory impairment. (Diabetes Care. 2004 Feb;27(2):633-4; author reply 634-5).

The present case report shows that a low-carbohydrate, high-fat diet improves glycemic control, reduces body weight and may prevent the development of end-stage renal failure in an overweight patient with type-2 diabetes.

Furthermore, it raises the concern that the obesity caused by the combination of a high-carbohydrate diet and insulin may have contributed to the patient’s failing kidney function.

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Nielsen JV, Westerlund P, Bygren P. A low-carbohydrate diet may prevent end-stage renal failure in type 2 diabetes. A case report. Nutrition & Metabolism 2006, 3:23 (14 June 2006). © 2006 Nielsen et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0).

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