The kidneys have millions of blood vessels, and since diabetes is really a ‘disease of the blood vessels’, this means the kidneys are very susceptible to harm.
By Shelley Diamond, BScPhm
Illustration by Martin Bregman
However, you can play a role in helping your patients delay or avoid diabetic nephropathy (DN) with appropriate management and monitoring. In fact, if kidney disease is diagnosed early, during microalbuminuria, you can make recommendations to avoid progression to end-stage renal disease (ESRD).
The first clinical evidence of DN is microalbuminuria (leakage of albumin into the urine; early on, it is below the threshold to be identified with a urine dipstick). Within a 10-year period, 20-40 per cent patients will progress from microalbuminuria to overt nephropathy (where albumin can be picked up by doing a urine dipstick) and another approximately 20 per cent will progress to ESRD.
In half of patients with type 1 diabetes with overt nephropathy, ESRD develops within 10 years, and in more than 75 per cent by 20 years in the absence of treatment. For people with type 2 diabetes, a larger percentage have microalbuminuria and overt nephropathy at or shortly after diagnosis of diabetes. This is largely due to the fact that the disease may have been present for several years before the diagnosis is made.
Usually there are no symptoms with diabetic nephropathy until the kidneys are functioning at a very low rate. When symptoms do occur, they are non-specific and usually include insomnia, anorexia, gastrointestinal symptoms, weakness and difficulty concentrating.
Studies have shown that race, genetic susceptibility, hypertension, hyperglycemia, hyperfiltration, smoking, advanced age, male sex, and a high-protein diet are risk factors for the development of DN.
How to help your patients:
Encourage reaching target blood glucose levels.
When blood glucose levels are elevated, the kidneys can become damaged. This is especially important for younger people with diabetes since they will have more years where damage can occur.
Make sure blood pressure is at target and the correct medications have been prescribed.
Any increase in blood pressure, even a small amount, can cause a more dramatic effect on the rate at which the disease progresses. The recommended medications for people with diabetes to help protect the kidneys are angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs). Note: their impact on protecting the kidneys is independent of their effect on blood pressure.
Ensure that regular monitoring of kidney function takes place at least once a year.
An ACR ratio, urine albumin/creatinine (>2.0mg/mmol) and eGFR (≤60 mL/min) can detect early kidney damage.
Recommend that your patients not smoke.
Smoking is an independent risk factor for the development of DN and is associated with an accelerated loss of renal function, an increased risk for ESRD, and decreased survival on commencement of dialysis.
Recommend avoidance of certain medications during acute illness.
When someone with diabetes is ill and dehydrated, as a result of vomiting and/or diarrhea, some medications can further reduce kidney function and are best avoided (i.e. medications are stopped temporarily). These include:
- Non-steroidal anti-inflammatory drugs
- Direct renin inhibitors
Other medications have reduced clearance and increased risk for adverse effects when patients are dehydrated or are unable to maintain adequate fluid intake. These include:
DN remains the leading cause of ESRD in developed countries. A multifactorial approach which includes reaching targets for blood glucose and blood pressure in addition with the use of ACEIs and ARBs, smoking cessation and regular monitoring, can significantly reduce the progression. Consider a ‘kidney protection discussion’ with your next diabetes medication review.