For individuals with diabetes who develop severe kidney damage, peritoneal dialysis is a treatment option that uses the natural lining of the abdomen to filter waste from the blood. The care for these patients involves careful coordination to handle both the demands of dialysis and the challenges of controlling blood sugar.
Diabetes and Progressive Kidney Damage
Diabetes mellitus is a primary cause of chronic kidney disease (CKD) and its final stage, end-stage renal disease (ESRD). Both Type 1 and Type 2 diabetes can lead to kidney damage, a complication known as diabetic nephropathy. Persistently high blood glucose levels slowly damage the small blood vessels within the kidneys, which are part of the filtering units called nephrons.
This damage thickens the blood vessels and scars the nephrons, impairing the kidneys’ ability to effectively filter waste and excess fluid from the blood. Initially, the kidneys may leak small amounts of a protein called albumin into the urine, a condition called microalbuminuria. As damage progresses, protein leakage increases, and the kidneys’ filtering capacity, measured as the glomerular filtration rate (GFR), declines.
This progressive loss of function leads to CKD and can advance to ESRD, where waste products build to toxic levels. When kidney function drops to less than 15 percent of normal, renal replacement therapy, such as dialysis or a kidney transplant, is required to sustain life.
The Mechanics of Peritoneal Dialysis
Peritoneal dialysis is a treatment for kidney failure that utilizes the peritoneum, the natural membrane lining the abdominal cavity, as a filter. The process requires minor surgery to place a soft tube, a peritoneal dialysis (PD) catheter, into the abdomen. This catheter acts as a port for introducing and removing a cleansing fluid called dialysate.
The procedure involves an “exchange” with three steps: filling, dwelling, and draining. First, dialysate is infused into the peritoneal cavity, which takes about 20 to 30 minutes. The dialysate contains a type of sugar that draws waste products and excess fluid from the blood across the peritoneal membrane.
During the “dwell time,” the dialysate remains in the abdomen for a prescribed period, allowing the patient to engage in normal activities. Finally, the used dialysate, now containing filtered waste, is drained into a collection bag and discarded, and the process is repeated.
Two main forms exist. Continuous Ambulatory Peritoneal Dialysis (CAPD) involves manual exchanges performed three to five times a day. Automated Peritoneal Dialysis (APD) uses a machine to perform exchanges automatically, at night while the patient sleeps.
Choosing Peritoneal Dialysis for Diabetic Kidney Failure
Peritoneal dialysis is a suitable option for many diabetic patients due to several advantages. A primary benefit is its gentle nature. PD removes fluid and waste slowly, which can lead to better hemodynamic stability and reduce stress on the cardiovascular system.
This approach is beneficial for diabetic patients, who often have coexisting cardiovascular conditions like hypertension and heart disease. The slower fluid removal helps avoid the low blood pressure episodes that can occur with in-center hemodialysis. This stability helps preserve the health of a heart already strained by diabetes.
Another consideration is the preservation of residual renal function (RRF), any remaining natural kidney function. PD may be better at preserving RRF compared to hemodialysis due to its gentler process. Maintaining even a small amount of RRF can contribute to better fluid balance and overall quality of life. PD is also a home-based therapy, offering patients greater flexibility and independence.
Controlling Blood Sugar During Peritoneal Dialysis
Standard dialysate solutions contain high concentrations of glucose to create the osmotic gradient needed to pull excess fluid and waste from the blood. A large portion of this glucose is absorbed into the bloodstream during each exchange, which can cause high blood sugar levels, or hyperglycemia.
This continuous glucose load complicates glycemic control and requires adjustments to the patient’s diabetes management plan. Oral medications like metformin are discontinued, and other oral agents may need dose adjustments. Consequently, many diabetic PD patients require insulin, which can be injected or added directly to the dialysate bags for intraperitoneal delivery.
Monitoring blood sugar also presents difficulties, as the standard Hemoglobin A1c (HbA1c) test can be unreliable in patients with ESRD. Continuous glucose monitoring (CGM) is an effective tool to overcome this. CGM devices use a sensor under the skin to track glucose levels in real-time, helping to tailor insulin doses more precisely. Using alternative PD solutions with less glucose or a different agent, such as icodextrin, can also help.
Managing Additional Health Issues in Diabetic PD Patients
Diabetic patients on peritoneal dialysis face other health challenges that require management. These include:
- Peritonitis: A heightened risk of peritonitis, an infection of the peritoneal membrane, exists. It can cause abdominal pain, fever, and cloudy dialysate, and may require hospitalization or a switch to hemodialysis. Strict adherence to sterile techniques during exchanges is the primary method of prevention.
- Cardiovascular Health: Diabetes and kidney disease are both risk factors for heart disease. Glucose absorption from dialysate can worsen dyslipidemia (abnormal blood fat levels) and inflammation. Management includes controlling blood pressure, managing cholesterol, and addressing fluid overload.
- Nutritional Management: Peritoneal dialysis can cause significant protein loss through the dialysate, leading to malnutrition. Patients need a specialized diet high in protein while limiting phosphorus, potassium, and sodium to maintain immune function and overall health.
- Peritoneal Membrane Damage: Long-term exposure to high-glucose dialysis solutions can damage the peritoneal membrane over time, reducing its effectiveness as a filter.