Read this 2007 paper published in the American Journal of Physiology: https://journals.physiology.org/doi/full/10.1152/ajprenal.00149.2007
It's actually pretty straight-forward: insulin resistance plus insulin causes high blood pressure regardless of restrictions in dietary sodium intake.
And the inverse is pretty straight-forward as well: healthy insulin sensitivity does not yield high blood pressure regardless of spikes in insulin or increases in dietary sodium.
To summarize, insulin is the sodium-retention pump. When it's added to an unhealthy person, the signal for blood pressure increase is overwhelming. When piles of salt and/or insulin are added to a healthy person, there is no strong signal to increase blood pressure.
Any management of high blood pressure through medication/mineral imbalance (ie - salt restriction, calcium or potassium manipulation, diuretic, or beta blocker) is a mild symptom reducer AT BEST. Of course, this symptom reduction comes at incredible costs to other organ systems, since its exact method of action is the disruption of various health systems throughout the body. The restoration of health, therefore, is the only cure for hypertension. Specifically, the restoration of insulin-sensitivity is the cure. In the many medical studies on type 2 diabetes reversal, all participants had a dramatic drop in blood pressure that exceeds any drop which could be obtained from salt restriction and hypertensive medications combined: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5928595/.
In wider reviews of the literature (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6520897/#B110-nutrients-11-00766), what the reader discovers is that there are many different names for the manifestation of metabolic diseases, but they all intertwine at the development of insulin resistance and persistent rampant inflammatory response. In one person, the primary manifestation may be atherosclerotic plaque buildup. In another, the primary manifestation may be weight gain. In another, the primary manifestation is hypertension; and so on. In all cases, all manifestations are up for grabs. The onlooker may only see one manifestation prominently; and the inclination is to throw one diagnostic name on that person (eg - hypertension, OR hypercholesterolemia, OR type 2 diabetes). But all manifestations are readying themselves underneath the surface, without a care about the diagnostic name chosen. The body doesn't care at all whether it obtained the name "prediabetes" or "type 2 diabetes". In both cases, blood pressure is mismanaged. That could showcase as LOW blood pressure, HIGH blood pressure, or even BOTH. Yes. You read that right. An exhausted person who is incredibly unhealthy may run very high blood pressures most of the time, and therefore be incapable of managing the normal healthy increases required from life when he stands up from tying his shoes.
Statistical analyses have been unhelpful. It's long been known that a diagnosis of high blood pressure doubles that person's risk of prediabetes. What those analyses miss is mechanism and direction of causation. They merely observe correlations and prevalence of correlation. And, of course, this all requires placing people in neat little bins of specific diagnostic names. To be clear, what's easier to catch: a high blood pressure number or chronic unregulated insulin? People with ridiculously unhealthy insulin response can land at "normative" glucose numbers many times before the clinician finally discovers an awful insulin relationship under the surface. Thus, although correlation is cute, it isn't a rigorous science. In the rigors of science, we work to understand mechanisms and really don't care at all what the correlational statistics say. In this particular case, there isn't a great alternative to slicing the data pie anyway. The data pie still says prediabetes has strong correlation to hypertension. If we ignore those stats and simply focus on known biology, unhealthy insulin management is causal for high blood pressure. That is not in dispute.
Regardless of what names we want to slap on someone to label him or her, restoration of health is the cure. In the review of type 2 diabetes reversals, hypertension disappeared in the responding participants. And in the 2007 paper discussing mechanisms, we find that a healthy, insulin-sensitive individual cannot run high blood pressure no matter how much salt and insulin you add to his system. Meanwhile, an unhealthy, insulin-resistant individual runs mismanaged blood pressure while medicated and salt-restricted UNTIL he restores health and insulin-sensitivity.