By Mark Abrahams, MD
According to the National Institutes of Health (NIH), approximately 40% of adults with diabetes have some degree of chronic kidney disease (CKD).1 That’s a lot of patients—perhaps more than one might think.
What should we be doing differently for these patients? Sure, they should be getting an angiotensin-converting enzyme (ACE) inhibitor or an angiotensin receptor blocker (ARB) for renoprotection, and blood pressure and lipids should be aggressively managed, but how does (or should) our approach to managing their antidiabetic therapy change?
We might consider taking a more aggressive approach to their glycemic control. In clinical trials, tight glycemic control has been shown to be the primary determinant of decreased microvascular complications.1 However, once we’ve decided how aggressively to manage glycemia, the choice of which antidiabetic to use (and how to dose it) is especially important in these patients.
Unfortunately, when the therapeutic strategy is to maximize glycemic control, the risk of hypoglycemia also increases - in both frequency and severity.2 Patients taking oral antidiabetics that are primarily eliminated by the kidneys are particularly susceptible.1 Furthermore, it should be noted that older patients are also at higher risk.3
Dosing errors are common in CKD patients and can cause poor outcomes.3 Drugs cleared renally should be dose-adjusted based on creatinine clearance or estimated glomerular filtration rate (eGFR). Dose reductions, lengthening of the dosing interval, or both may be required.3
As metformin is nearly 100% renally excreted, it is contraindicated in a number of patients: when serum creatinine is higher than 1.5 mg/dL in men or 1.4 mg/dL in women, in patients older than 80 years, or in patients with chronic heart failure. The primary concern here is that other hypoxic conditions (e.g., acute myocardial infarction, severe infection, respiratory disease, liver disease) may increase the risk of lactic acidosis. Because of this danger, and despite the fact that metformin is usually the recommended first-line treatment for type 2 diabetes, one should use caution when considering metformin in patients with renal impairment.3
Similarly, sulfonylureas should be used with care in diabetics with CKD. The clearance of both sulfonylureas and their metabolites is highly dependent on kidney function. As such, severe and sustained episodes of hypoglycemia due to sulfonylurea use have been described in dialysis patients.2
Regardless of which antidiabetic agent is selected, HbA1c and kidney function should be regularly monitored and the antidiabetic regimen appropriately adjusted. As patients with type 2 diabetes tend to progress over time, most will require a combination of agents to achieve desired glycemic control. These combinations should be chosen carefully in patients with CKD.1
Finally, awareness of and screening for renal impairment in diabetics is a necessary precursor to successful intervention. In these patients, CKD is underdiagnosed and undertreated, and awareness of the disease is low among providers and patients alike.1
Early detection of disease via eGFR or urinary albumin excretion can lead to timely, evidence-based intervention and help prevent or delay progression of CKD. The benefit? Improved kidney and cardiovascular outcomes, and lower associated costs.1
References:
- Bakris GL. Recognition, Pathogenesis, and Treatment of Different Stages of Nephropathy in Patients With Type 2 Diabetes Mellitus. Mayo Clin Proc. 2011;86:444-456.
- Cavanaugh KL. Diabetes Management Issues for Patients With Chronic Kidney Disease. Clin Diab. 2007;25:90-97.
- Munar MY, et al. Drug Dosing Adjustments in Patients With Chronic Kidney Disease. Am Fam Physician. 2007;75:1487-1496.
Courtesy of MedPage Today
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