Nutritional Concerns in Diabetic Nephropathy SUSAN THOM, RD, LD, CDE St. Vincent Charity Hospital Cleveland, Ohio

Protein probably is the most understud-. they might be taught in the context of ied macronutrient in the diet of those an exchange regimen is listed in with diabetes. It has gained research interest in the last several years due to a number of factors: 1) the &dquo;ideal&dquo; diet prescription for those with diabetes remains elusive; 2) the treatment of nondiabetic clients with renal disease parallels the same concerns; 3) in the United States, one of every three or four clients entering a renal support program has diabetes; and 4) about 30% of clients with insulin-dependent diabetes mellitus (IDDM) and 15% of those with noninsulin-dependent diabetes mellitus (NIDDM) will develop end stage renal disease (ESRD).’I The first of five described stages of diabetic nephropathy actually begins at the time of the clinical diagnosis of diabetes. Glomerular hyperfiltration, an abnormally increased glomerular filtration rate (GFR), is most characteristic in .IDDM. It is at this early stage that proponents of low-protein diets advocate stronger patient education about this particular complication.2 In fact, the Recommended Dietary Allowances (RDA) for protein at 0.8 grams/kg/day should be taught as the normal amount of protein versus a &dquo;low&dquo; protein intake. This approach may help the client accept restrictions that may be necessary. Actually, the restriction is relative because the typical American consumes two to three times the RDA in protein every day. The protein content of various typical foods in the diet as

Charity Hospital. Correspondence to Susan Thom, RD, LD, CDE, St. Vincent Charity Hospital, 2354 Hillcrest Lane, Parma, OH 44134.

Sources of Protein

Table 1. A low-protein diet decreases the glomerular filtration rate in patients with all types of chronic renal disease, including diabetic nephropathy. In microalbuminuric patients with diabetes (range of albumin excretion 25250 mg/day), a low-protein diet will cause a reduction in urinary albumin excretion without any change in GFR. Replacement of animal protein with vegetable protein has demonstrated a slower rate of GFR decline in patients with diabetic nephropathy.3-5 Progression of nephropathy to the second stage, glomerular sclerosis, is highly variable. Patients in this stage are normoalbuminuric, but structural lesions are common, including mesangeal expansion and increasing basal membrane thickness. This stage may manifest itself in individuals with diabetes of only one to fifteen years duration, or in those with long-term diabetes of greater than fifteen years duration. Those who go on to develop nephropathy will have severe and extensive lesions histologically. This higher risk group includes patients with a GFR > 150 mL/min. This rate rarely is seen in those with glycosylated hemoglobin values less than 8.0%. Thus, euglycemia, and probably a lower protein intake, could be beneficial in delaying further progression of diabetic

nephropathy.2 The third stage of diabetic nephropathy is termed &dquo;incipient nephropathy&dquo;

Ms Thom is a Clinical Manager for the Excelle Health Enrichment Programs at St. Vincent

Table 1.

and is characterized by an increased urinary albumin excretion rate (UAER), or microalbuminuria. This rate now is used as a well-established marker of early renal involvement in

diabetes. Microalbuminuria is diagnosed when the UAER reaches 20 to 200 micrograms per minute, or 30 to 300 milligrams per 24 hours in two of three urine samples collected within 6 months. At this third stage of diabetic nephropathy, blood pressure usually is elevated compared with healthy

subjects. Hypertension

is the single most imfactor shown to accelerate the portant progression of established diabetic nephropathy and contributes to other diabetes-related morbidity and mortality such as retinopathy and heart disease. Glomerular closure may occur in this stage. If left untreated, 80% of microalbuminuric patients will develop overt nephropathy. 6.7 Thus, dietary and pharmacologic interventions are necessary at this stage. The fourth stage of diabetic nephropathy is known as &dquo;overt nephropathy&dquo; and is defined by persistent proteinuria (greater than 500 milligrams per 24 hours total protein excretion) corresponding to UAER values of more than 200 micrograms per minute (often termed macroalbuminuria). To make a definitive diagnosis, protein excretion is measured at greater than 500 milligrams per 24-hour period in four

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consecutive 24-hour urine samples. Progression to azotemia (rising serum creatinine and blood urea nitrogen levels) usually occurs within I to 5 years once the proteinuria becomes continu-

Table 2.

Diabetic Renal Diet Protocol

Nephrotic syndrome ensues when protein losses exceed 4 grams per day and may be as high as 20 to 30 grams per day. This fourth stage frequently is associated with other diabetic complications, including retinopathy and autonomic neuropathies, such as diabetic gastroparesis and enteropathy. With such high losses of protein, early satiety, and failing appetite, supplemental protein may be required at this point to ous.






strength to handle each emerging complication. In addition, insulin requirements drop drastically as insulin halflife is extended with the absence of ’

kidney metabolic function. Recipes for low-sugar, high-protein beverages as daily supplements or commerciallyavailable formulas may be necessary. Renal dietitians can prescribe appropriate supplements based on protein requirements as determined by kinetic

modeling.’ &dquo;

. The fifth and last stage of diabetic

.. ’

Table 3. Diabetic Nephropathy: Recommendations

Laboratory Parameters and Dietary

nephropathy is end-stage renal failure. When uremia approaches, a strategy for renal replacement therapy (RRT) must be considered. The most crucial considerations involve: (1) ensuring satisfactory symptomatic treatment of the uremic patient with diabetes, which entails management of hyperglycemia, hypertension, fluid retention, and dietary restrictions; and (2) deciding which modality of RRT to use, such as hemodialysis, continuous ambulatory peritoneal dialysis, or renal transplantation. RRT usually is started earlier in patients with diabetic nephropathy than in uremic nondiabetic counterparts due to the illness involved. Although RRT may be initiated when the GFR falls below 10 mL/min, it may be initiated in the patient with diabetes -at levels between 5 to 10 mLJmin. A final option to consider is death as the natural progression of the renal disease to its conclusion. Often neglected, this option may be considered when rational choices have been analyzed.

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While on dialysis, patients must conbalance between macronutrients, micronutrients (vitamins and minerals), and electrolytes. A standard protocol for managing diabetic renal patients on dialysis is described in Table 2. It may be worthwhile for the practitioner to refer to the carbohydrate portion of the meal plan as &dquo;carbohydrate-modified,&dquo; since the inclusion of more simple carbohydrates may be required to meet caloric needs and prevent hypoglycemia. A description of the stages of diabetic nephropathy and the protein recommendations at each of these stages is summarized in Table 3. sume a


1. Thom S, ed. Low protein diets in diabetic nephropathy. In: On the cutting edge. [Newsletter of the Diabetes Care and Education Practice Group.] Chicago: American Dietetic Association,

1991;12(4):1-22. 2. Kidney disease. In: Herman WH, ed. The prevention and treatment of complications of diabetes mellitus: a guide for primary care practitioners. Atlanta: Department of Health and Human Services, Public Health Service, Centers for Disease Control, Center for Chronic Disease Prevention and Health Promotion, Division of Diabetes Translation, 1991:6-1 to 6-5. 3. DeFronzo R. Nephropathy. In: Lebovitz HE, ed. Therapy for diabetes mellitus and related disorders. Alexandria, Va: American Diabetes Association, 1991:248-60. 4. Zeller KR. Low protein diets in renal disease. Diabetes Care 1991;14:856-66.

5. Nuttall F, Gannon MC. Plasma glucose and insulin response to macronutrients in nondiabetic and NIDDM subjects. Diabetes Care 1991;14: 824-38. 6. Nephropathy. In: Sperling MA, ed. Physician’s guide to insulin-dependent (type I) diabetes : diagnosis and treatment. Alexandria, Va: American Diabetes Association, 1988:115-22. 7. Rosenstock J, Raskin P. Early diabetic nephropathy: assessment and potential therapeutic in-

terventions. In: Clinical diabetes reviews: volume I. Alexandria, Va: American Diabetes Association, 1987:128-47. 8. Kaysen GA. Nutritional management of nephrotic syndrome.J Renal Nutr,1992;2:50-8.

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Nutritional concerns in diabetic nephropathy.

537 Nutritional Concerns in Diabetic Nephropathy SUSAN THOM, RD, LD, CDE St. Vincent Charity Hospital Cleveland, Ohio Protein probably is the most u...
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