The CDC estimates that 31% of U.S. adults have hypertension, with that proportion rising to nearly 70% among adults with diabetes – and those with both conditions are at increased risk for complications including stroke, coronary artery disease (CAD), peripheral artery disease (PAD), eye problems, kidney disease and neuropathy. 1,2
Fortunately, hypertension management strategies can go a long way towards reducing these complications. Data from the U.K. Prospective Diabetes Study (UKPDS) indicated that decreasing mean systolic BP by 10 mm Hg resulted in a 12% reduction in the risk for diabetes-related complications, a 15% reduction in diabetes-related deaths and an 11% reduction in myocardial infarction.3
There are many medications and lifestyle modifications available to help patients with diabetes lower their BP, but recognizing hypertension is the first step. Clinicians should check BP levels at every appointment to confirm that patients are within the healthy range. The American Diabetes Association (ADA) recommends a slightly lower cut-off point for diagnosing hypertension in patients with diabetes because of the well-established risk for cardiovascular disease: BP ≥130/80 mm Hg vs. BP ≥140/90 mm Hg.
For adult diabetes patients with slight BP elevations (130-139 mm Hg systolic BP, 80-89 mm Hg diastolic BP) diet and exercise may be sufficient to achieve target BP levels. But if no changes occur after three months, clinicians should consider initiating drug therapy.
Adult patients with systolic BP ≥140 mm Hg and diastolic BP ≥ 90 mm Hg should receive medication upon diagnosis, in addition to lifestyle counselling.
Angiotensin-converting enzyme (ACE) inhibitors or angiotensin II receptor blockers (ARB) are the standard of care for treating hypertension in patients with diabetes, according to the ADA. There are many available, but lisinopril and captopril are among the most commonly prescribed.
ACE inhibitors reduce a patient’s risk for MI and stroke and delay kidney disease progression, and are most effective among patients with type 1 diabetes, hypertension and macroalbuminuria.4 Clinicians should be aware that ACE inhibitors can raise serum potassium levels, and should not prescribe these medications to patients with a history of angioedema or bilateral renal artery stenosis. Additionally, some patients may develop a dry cough with ACE inhibitor therapy and may benefit from a switch to an ARB.
ACE inhibitors are class D medications, meaning they have proven teratogenic effects and should not be prescribed to pregnant women. Be sure to counsel women who may become pregnant or are considering pregnancy about the use of effective contraception while taking these medications.
Remember that targed BP levels for pregnant women with diabetes are lower, with systolic BP ranging between 110–129 mm Hg, and diastolic BP ranging from 65–79 mmHg. Hypertension medication options for pregnant patients with diabetes include methyldopa, nondihydropyridine calcium channel blockers, and select beta-blockers such as labetalol and carvedilol.17
Like ACE inhibitors, ARBs prevent progression of diabetic kidney disease, and are currently recommended as a first-line alternative therapy for patients who cannot tolerate ACE inhibitors. Commonly used ARBs include irbesartan, losartan and telmisartan.
Data from a number of randomized controlled trials have demonstrate that ARBs are more effective than other hypertension medications in slowing glomular filtration rate (GFR) decline and kidney failure onset among patients with type 2 diabetes and macroalbuminuria.7 Caution should be used when considering an ARB for patients who have had ACE inhibitor-induced angioedema.
Combining ACE inhibitors and ARBs
Combining ACE inhibitors and ARBs is not recommended for most patients with diabetes, but clinicians might consider combination therapy for extremely hypertensive patients. In this case, the patient should be monitored for hyperkalemia.
Data from the ONTARGET study indicated that combining the two drugs can harm the kidneys without providing any additional benefit. Data from another 2010 study indicate that patients who had BP > 160/100 mm Hg experienced more severe renal damage than those with lower BP readings. However, in the same study patients with proteinuria or GFR levels < 60 mL/min did not experience kidney damage from the combination.
If ACE inhibitors and ARBS are insufficient for reducing BP to target levels, clinicians should consider adding a diuretic to the treatment regimen. The type of diuretic prescribed should depend on glomerular filtration rates (GFR).
The ADA recommendations include a thiazide diuretic for patients with GFR levels > 30 ml x min/1.73 m2, as GFR readings of this level or more indicate only minimal evidence of kidney dysfunction. Thiazide diuretics, such as hydrochlorothiazide and chlorthalidone, provide additional antihypertensive effects when combined with ACE inhibitors or ARBs. But these drugs can cause changes in glucose metabolism, volume depletion and hypokalemia, so it is important to use lower or moderate dosages to minimize this risk. Clinicians should monitor potassium levels and provide supplements as necessary.