A reading of 133/98 mmHg is abnormal, and the diastolic number (the bottom one, 98) is the main concern. Under current guidelines from the American College of Cardiology and American Heart Association, any diastolic pressure at or above 90 places you in the Stage 2 hypertension category regardless of where the systolic lands. A systolic of 133 is only mildly elevated on its own, but that high diastolic narrows the gap between the two numbers in a way that signals a distinct hemodynamic pattern worth understanding.
How This Reading Gets Classified
Blood pressure categories are determined by whichever number falls into the higher stage. Under the 2017 ACC/AHA framework, a systolic pressure of 130 to 139 qualifies as Stage 1 hypertension, while a diastolic of 90 or above qualifies as Stage 2. Because the higher category governs the overall classification, 133/98 is classified as Stage 2 hypertension. That classification matters because it typically triggers a conversation about starting medication in addition to lifestyle changes, rather than trying lifestyle measures alone for a few months first.
Under the older JNC7 classification (still referenced in some settings), Stage 1 hypertension starts at 140/90, so a reading of 133/98 would have been labeled Stage 1 based on the diastolic crossing 90 while the systolic remained below 140. That older framework defined this pattern as isolated diastolic hypertension, or IDH. Under the newer, stricter thresholds, both numbers are technically elevated, but the diastolic is doing the heavier lifting.
What the Narrow Pulse Pressure Tells You
The difference between the two numbers, called pulse pressure, is only 35 mmHg here (133 minus 98). A typical pulse pressure in a healthy adult runs somewhere in the 40 to 60 range. A narrow gap like this points to a different underlying physiology than what you see in the more common pattern of high systolic with normal or low diastolic, which tends to show up in older adults with stiff arteries. In that scenario, the arteries have lost their elastic recoil, driving the top number up and the bottom number down, which widens the pulse pressure. Your reading is doing the opposite.
A disproportionately high diastolic with only a mild systolic rise is more commonly seen in younger and middle-aged adults. Research on arterial stiffness has found that people with this diastolic-predominant pattern tend to have more compliant (flexible) large arteries compared to those with isolated systolic hypertension, but they show higher resistance in their smaller arteries. Studies in the Dallas Heart Study confirmed that people with isolated diastolic hypertension had lower aortic stiffness measures than those with systolic hypertension, while having elevated vascular resistance downstream.
Why the Diastolic Runs High
The core mechanism behind an elevated diastolic reading is increased systemic vascular resistance, meaning the small arteries throughout your body are squeezing tighter than they should be. Diastolic pressure reflects what happens between heartbeats, when the heart is relaxing and filling. If the resistance vessels stay constricted during that relaxation phase, the pressure in the system doesn’t drop as far as it should, and the diastolic number stays high. Neurohormonal signals and smooth-muscle contraction at the level of small resistance arteries drive this pattern.
A Finnish longitudinal study tracking young adults over several years found that systemic vascular resistance measured at baseline independently predicted who would develop elevated diastolic blood pressure years later. In other words, the high resistance comes first, and the blood pressure reading follows.
Several modifiable factors push vascular resistance up. Excess body weight is one of the strongest. Data from the United States found that the prevalence of isolated diastolic hypertension climbed steadily with body mass index, and people with a BMI of 30 or above had a notably higher rate of IDH. Being male, being middle-aged (roughly 40 to 59), and being physically inactive all independently raised the risk as well. An Indian population study found similar associations, with physical inactivity and BMI standing out as the strongest modifiable predictors.
Could the Reading Be Inaccurate
Before worrying too much about a single 133/98 reading, it is worth asking whether the measurement was accurate. Blood pressure is surprisingly sensitive to the conditions under which it is taken. A cuff that is too small for your arm is one of the most common sources of error, and it inflates the diastolic number more than most people realize. A randomized crossover trial found that using a regular-sized cuff on an arm that needed a cuff one size larger added roughly 2 mmHg to the diastolic reading, but using a cuff two sizes too small inflated the diastolic by about 7 mmHg. On an arm that genuinely needs a large or extra-large cuff, a standard cuff could push a true diastolic of 91 up to 98 on the readout.
Talking, crossing your legs, a full bladder, caffeine within 30 minutes, and stress or anxiety can also elevate a reading. The white-coat effect, where blood pressure rises simply from being in a medical setting, is extremely common. A large Hungarian registry study of ambulatory blood pressure monitoring found that among patients whose office readings fell in the high-normal range, over half actually had masked hypertension (higher readings outside the office) while over a quarter showed a white-coat pattern (higher readings only in the office). A single office reading of 133/98 should be confirmed with repeat measurements on different days, ideally with a properly sized cuff and a seated rest period of at least five minutes beforehand. Home monitoring or 24-hour ambulatory monitoring gives a much clearer picture.
The Risk Question
This is where the evidence gets complicated, and where the research community has gone back and forth for decades. Everyone agrees that a systolic number above 140 raises cardiovascular risk. The independent contribution of a high diastolic, especially when the systolic isn’t very high, is more contested.
A large study published in JAMA looked at whether isolated diastolic hypertension (defined by both the JNC7 and 2017 ACC/AHA cutoffs) was linked to heart disease, stroke, heart failure, or kidney disease over years of follow-up. It found no statistically significant increase in any of those outcomes for people whose only abnormality was an elevated diastolic reading. That study was influential and led many clinicians to view IDH as relatively benign compared to systolic hypertension.
But other researchers have pushed back, arguing that the inconsistent findings across studies reflect differences in populations, follow-up lengths, and how IDH is defined rather than a true absence of risk. A 2022 review in Hypertension made the case that IDH is an underrated risk factor, and that the mixed results stem partly from the fact that IDH tends to occur in younger, healthier people who haven’t yet accumulated enough cardiovascular events to show up in shorter studies. A study of older adults in the Cardiovascular Health Study found that when both systolic and diastolic numbers were elevated, the risk of heart failure and death was at least as high as with isolated systolic hypertension, and possibly somewhat higher for mortality.
For kidneys specifically, a study in the Chronic Renal Insufficiency Cohort looked at people who already had kidney disease and found no additional worsening of kidney outcomes or cardiovascular events from isolated diastolic hypertension over the study period.
What does this mean for you? A 133/98 reading probably doesn’t carry the same urgency as a 170/98 reading, but it isn’t harmless either. The diastolic elevation reflects real vascular changes that, left unaddressed over years, are associated with measurable harm.
Diastolic Pressure and the Brain
One area where elevated diastolic pressure appears to cause damage relatively early is the brain. A longitudinal study following adults from their early forties found that higher diastolic blood pressure at ages 40 to 44 was associated with declining cognitive performance over the following 12 years, particularly on tests of processing speed. Each 10 mmHg increment in diastolic pressure at that age was also linked to a meaningful increase in white matter lesions in the brain, the small areas of damage in the brain’s wiring that accumulate silently and are associated with future dementia risk. The relationship was present even after accounting for systolic pressure.
This finding is particularly relevant for someone with a reading like 133/98, because this diastolic-predominant pattern is most common in exactly the age group (40s and 50s) where the brain appears most vulnerable to diastolic pressure effects. By the time systolic hypertension becomes the dominant concern in your sixties or seventies, years of unaddressed diastolic elevation may have already done silent damage.
Sleep Apnea and Other Treatable Causes
A persistently elevated diastolic reading, especially one that doesn’t respond well to standard treatment, should prompt your doctor to consider secondary causes of hypertension. One of the most underdiagnosed is obstructive sleep apnea. Research has shown that early or subclinical sleep apnea tends to raise diastolic pressure first, even before the systolic number climbs. A study of periodic health screening found that subjects with obstructive sleep apnea had diastolic pressures averaging about 4 mmHg higher than matched controls, with no corresponding increase in systolic pressure. Another study in non-hypertensive patients found that severe sleep apnea was associated with morning diastolic readings averaging around 86 mmHg compared to roughly 79 in people without significant apnea, and that the severity of apnea independently predicted diastolic elevation regardless of obesity, age, or sex.
Primary aldosteronism, a condition where the adrenal glands produce too much aldosterone, is another treatable cause found more often than previously thought. In one study of over 600 patients with essential hypertension, about 6 percent turned out to have primary aldosteronism, and the proportion rose sharply with the severity of hypertension. Nearly all of these patients had normal potassium levels, which means the classic textbook sign of low potassium is actually a poor screening tool. Biochemical screening with an aldosterone-to-renin ratio remains the most reliable way to catch this condition. Thyroid disorders, kidney artery narrowing, and certain medications (especially NSAIDs like ibuprofen, decongestants, and some antidepressants) can also push diastolic pressure up disproportionately.
Bringing the Numbers Down
Lifestyle changes can meaningfully lower diastolic blood pressure, and for a reading of 133/98 they are worth pursuing whether or not medication is started. Regular aerobic exercise alone has been associated with diastolic reductions of roughly 2 mmHg on average, but the DASH dietary pattern (rich in fruits, vegetables, and low-fat dairy, and lower in sodium) has shown larger effects, with diastolic drops around 3 mmHg compared to a typical American diet. When the DASH diet was combined with exercise and weight loss in a clinical trial, diastolic pressure dropped by about 10 mmHg on average, a result that would bring a reading of 98 close to normal range. Even the DASH diet alone, without exercise or weight loss, produced diastolic reductions averaging about 7.5 mmHg in that trial.
Exercise type may matter too. A recent randomized trial in women with elevated blood pressure found that combined resistance and aerobic training produced a greater reduction in diastolic pressure (about 7 mmHg) than aerobic-only training (about 5 mmHg), suggesting that adding some strength work to your routine could be especially helpful when the diastolic is the problem number.
When medication is needed, research from controlled trials has shown that drug therapy lowers diastolic pressure more effectively than dietary changes alone in the short term. One trial found that the beta-blocker atenolol lowered diastolic blood pressure by about 12 mmHg, compared to roughly 8 to 9 mmHg with weight loss alone. Adding weight loss to a diuretic enhanced the effect significantly, producing diastolic drops averaging about 15 mmHg. Your doctor’s choice of medication will depend on your overall profile, but ACE inhibitors, ARBs, calcium channel blockers, and low-dose diuretics are all commonly used first-line options for diastolic-predominant hypertension.
Elevated Diastolic Pressure During Pregnancy
If you are pregnant or planning to become pregnant, a diastolic reading of 98 carries additional and specific significance. A large population-based study found that women whose diastolic blood pressure remained elevated from early to mid-pregnancy had roughly 1.8 times the risk of developing preeclampsia compared to women whose diastolic dropped during the same period. When that elevated diastolic was combined with preterm birth, the risk of preeclampsia more than doubled. Women who started pregnancy with Stage 1 hypertension and maintained elevated diastolic readings through mid-pregnancy had the highest rates of preeclampsia, reaching about 10 percent.
Diastolic blood pressure normally dips during the second trimester of pregnancy due to hormonal changes that relax blood vessel walls. A failure of that expected dip, or a persistently high diastolic reading through mid-pregnancy, is a warning signal that the placental vasculature may not be developing normally. Close monitoring and early involvement of a maternal-fetal medicine specialist is standard care in this scenario. Blood pressure targets during pregnancy differ from those for the general population, and medication choices are more restricted because some common antihypertensives can harm fetal development.
What a Pattern of 133/98 Looks Like Over Time
A single reading of 133/98 is a snapshot, and blood pressure fluctuates throughout the day. If repeated measurements confirm the pattern, though, the trajectory matters. In younger adults, isolated diastolic hypertension often represents an early stage on the road to full-blown combined hypertension. The same increased vascular resistance that holds the diastolic up eventually stiffens larger arteries as well, and over years the systolic number climbs to join it. Research on arterial stiffness has described this as a transition: young adults with IDH have flexible large arteries but high peripheral resistance, while older adults with isolated systolic hypertension have stiff central arteries but lower peripheral resistance. In between, many people pass through a phase where both numbers are elevated.
This means a 45-year-old with a reading of 133/98 who does nothing about it may well be looking at 160/95 a decade later. Addressing the modifiable drivers now, particularly excess weight, sodium intake, physical inactivity, and untreated sleep apnea, can slow or prevent that progression. The diastolic number in midlife is, in some respects, a canary in the coal mine: it signals vascular trouble at a stage when the damage is still largely reversible.