Anaemia:

a silent complication of diabetes

Tiredness and lethargy are associated with diabetes, but are usually due to uncontrolled blood glucose (sugar) levels. However there may be other causes of tiredness as in the rest of the population, and these include anaemia. Awareness of anaemia in diabetes is low, both among patients and health-care professionals. Yet if anaemia is diagnosed and corrected, the result can be a major change in quality of life. One cause of anaemia in people with diabetes is kidney disease.

Diabetes, the kidneys and anaemia. It is now known that anaemia occurs much earlier in the course of kidney disease than previously realized; specialists in kidney diseases and in diabetes have only recently begun to take notice of its importance at this early stage. Anaemia is a key indicator of early impairment of kidney function. Around a third of people with diabetes may develop kidney damage, and this progresses to impairment of kidney function in a significant proportion of such people.

Given the alarming increase in the prevalence of diabetes, renal impairment is likely to become much more widespread among the general population. Diabetes is already the leading cause of kidney failure in many countries. IDF statistics suggest there are more than 194 million people with diabetes world wide, and project that this will double by 2025.

Diabetes causes changes to the small blood vessels that supply the kidneys. Although the major concern for people who develop these changes is to prevent the progression of kidney damage, an important (and often overlooked) consequence of kidney failure is renal anaemia. This starts to develop from the early stages of impairment of kidney function even in people who are not yet on dialysis. The third National Health and Nutrition Examination Survey in the US (NHANES III) confirmed that poorer levels of kidney function are associated with lower haemoglobin levels and thus a higher prevalence and severity of anaemia.

Impaired function of erythropoietin

In healthy people erythropoietin, a protein formed in the kidney, stimulates the production of the red blood cells that carry oxygen from the lungs. However, under certain conditions, including diabetic nephropathy, renal failure, infection and tumour growth, the production of erythropoietin is in hibited or it saction impaired. Consequently, there are insufficient numbers of red blood cells, resulting in a low haemoglobin concentration and anaemia.

By definition, anaemia occurs when the body's level of red blood cells and therefore haemoglobin (the molecule in red blood cells which carries the oxygen) is abnormally low. The oxygen-carrying capacity of blood is thus reduced.
 

Tiredness affecting everyday life

Results of a pan-European survey in 2002 revealed that many people with diabetes report symptoms similar to those found in people with anaemia. More than half (53%) of the 1054 people with diabetes who were questioned said they often felt tired or lethargic. For many, the tiredness had a major impact on day-to-day activity. As many as 59% of people said they struggle to get through the working day, with 69% needing to get some sleep during the day. Eight percent said they were constantly tired.

The tiredness appeared to affect other areas of life, such as personal relationships and mental well-being. Relationships with loved ones and sexual drive suffered due to tiredness; more than a fifth believed their tiredness/lethargy made them feel down or depressed. Among those found to have anaemia or periods of tiredness for other reasons, the results were more marked: 27% felt down or depressed and 17% felt frustrated.
 

Low knowledge of link to anaemia

Many people with diabetes who feel tired come to attribute this to their diabetes. "The vast majority of people with diabetes are not aware of this complication of their condition, and they do not relate the fatigue or other symptoms to anaemia," commented Professor Marcello Amato, a consultant nephrologist in Prato, Italy.

It is the combination of lack of awareness and lack of routine screening for anaemia that causes the complication to be so often overlooked. Although most of the survey's participants had heard of anaema, only 24% had been given information about it (in the most cases verbally) and there was a poor overall understanding of causes of anaemia. As one person in Germany inaccurately said. "It's due to sugar, and possibly due to the stress of my studies;" while another in Belgium commented, "I thought it was related to smoking too much."
 

Routine tests not conducted

Too often, anaemia is never even considered. "As a team we didn't consider anaemia at all until last year. when we liaised directly with renal specialist nurses." explains diabetes nurse specialist Hilary Payne, who is also diabetes co-ordinator for East Kent UK." We were completely unaware of the percentage of patients with diabetes who suffer from anaemia. Often when patients complained of tiredness we would relate it to poor levels of blood sugar levels. But now, especially when the tiredness persists, we recommend checking for anaemia — and we are diagnosing it in a significant number of patients"

Although the European survey revealed that 88% of people diagnosed with diabetes are routinely tested for eye problems, 86% for high blood pressure and 85% for cholesterol and lipid (blood fat) levels, only 1% of respondents were aware of being tested for anaemia during routine visits to the doctor or nurse.

The dangers of not treating

If left untreated, anaemia can cause significant cardiac damage, as the heart has to work harder to circulate the limited amount of oxygen-carrying haemoglobin through the blood stream. Increases in cardiac output of up to 20 percent are commonly seen in people with anaemia. Left ventricular hypertrophy (LVH) is a condition featuring an enlarged, diseased heart that has to work progressively harder to pump blood around the body. The condition is very prevalent in people with diabetes prior to entering into dialysis, as a result of the high blood pressure these people suffer.

The cardiac complications of anaemia can be coupled with a significant impact on quality of life. It is not uncommon for people with diabetes to have suffered from anaemia for a number of years before receiving treatment. During this time, their career, family relationships and social life may have suffered significantly.
 

Self-administered treatment

Traditionally, treatment for anaemia has involved blood transfusions. However, this practice has been largely abandoned as it can be costly and is not without risk. Correction of anaemia with recombinant human rhEPO has now become standard therapy for treatment of anaemia in people with significant kidney impairment prior to dialysis, and has transformed the way in which the condition is now treated. This treatment works by mimicking the action of normal erythropoietin.

Erythropoietin has provided a safe and effective treatment of anaemiain people with kidney disease for over a decade. New studies are now underway to investigate the effects of anaemia correction with erythropoietin among people with diabetes and kidney impairment one recent study is the Anaemia Correction in Diabetes (ACORD), which will look at the effects of anaemia correction with erythropoietin on cardiovascular function in people with diabetic nephropathy.

Improved communication

The objective now is to get more patients checked for anaemia much earlier, and appropriately treated if they are diagnosed with the condition. However, to avoid unnecessary suffering from the symptoms of anaema, and prevent or minimize any cardio vascular damage, awareness-raising remains a challenge.

Closer liaison between renal and diabetic nurses is also important, so that people with diabetes and advancing kidney problems benefit from multi-team expertise with a more holistic approach. " While awareness of anaemia among renal nurses is now much better, it remains low among diabetes educators. By holding workshops and developing communication strategies, there is a mutually beneficial opportunity to share more information," says Karen Jenkins, renal anaemia nurse specialist in the UK, who is now helping to pioneer a series of study days with both renal and diabetic nurse specialists.

At the same time, people with diabetes themselves can become better informed. Helping people to understand their own disease and its complications will encourage them to become more proactive in seeking information. As the pan-European survey revealed, they are currently not given sufficient details. "I believe we have a lot of work ahead of us, not dust in educating people with diabetes, but also in meeting with GPs, making closer contact with diabetologists and ensuring nurses are given the right information." says Professor Amato.
 

References

1. Viberti GC, Marshall S, Beech R.Brown V, Derben P, Higson N, Home P, Keen H, Plant M, Walls J. Report on renal disease in diabetes. Diabetic Med 1996: 13: S6- 12.

2. Zimmet P, Shaw J, Murray S, Sicree R. The diabetes epidemic in full flight: forecasting the future. Diabetes Voice 2003; 48 (special issue on Prevention): 12-16.

3. Astor BC. Muntner P, LevinA, Eustace JA, Coresh J. Association of kidney function with anaemia: The Third National Health and Nutrition Examination Survey (1988-1994). Arch Intern Med 2002: 162: 1401-1408.

4. Drueke TB. Does early anaemiacorrection prevent complications of chronic renal failure? Clin Nephrol 1999; 51: 1-11.

S. Foley RN, Parfrey PS, Harnett JD, Kent GM, Murray DC, Barre PE. Theimpact of anemia on cardiomyopathy, morbidity and mortality in end-stage renal disease. Am J Kidney Dis 1996; 28: 53-61.

Nicola O'Connell is a freelance medical writer.

Duality of interest: this article was submitted on behalf of Roche Pharmaceuticals.
 

Roche Pharmaceuticals manufacturers and markets an erythropoietin preparation for therapeutic use.
 

This article was first published in Diabetes Voice, August 2003,Volume 48. Special Issue.