Cataracts and glaucoma are also more common among diabetics. It is also important to note that since the lens of the eye lets water through, if blood sugar concentrations vary a lot, the lens of the eye will shrink and swell with fluid accordingly. As a result, blurry vision is very common in poorly controlled diabetes. Patients are usually discouraged from getting a new eyeglass prescription until their blood sugar is controlled. This allows for a more accurate assessment of what kind of glasses prescription is required.
Potassium – as part of the electrolyte panel, which also includes sodium, chloride, and carbon dioxide (CO2); to evaluate and monitor the balance of the body's electrolytes. For example, low potassium can be seen in Cushing syndrome and Conn syndrome, two causes of secondary hypertension. Some high blood pressure medications can upset electrolyte balance by causing excessive loss of potassium or potassium retention.
Globally, black adults have among the highest rates of hypertension, with an increasing prevalence. Although white adults also have an increasing incidence of high BP, they develop this condition later in life than black adults and have much lower average BPs. In fact, compared to hypertensive white persons, hypertensive black individuals have a 1.3-fold higher rate of nonfatal stroke, a 1.8-fold higher rate of fatal stroke, a 1.5-fold higher mortality rate due to heart disease, and a 4.2-fold higher rate of end-stage renal disease (ESRD). 
In the 19th and 20th centuries, before effective pharmacological treatment for hypertension became possible, three treatment modalities were used, all with numerous side-effects: strict sodium restriction (for example the rice diet), sympathectomy (surgical ablation of parts of the sympathetic nervous system), and pyrogen therapy (injection of substances that caused a fever, indirectly reducing blood pressure).
[Guideline] Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. 2018 Jun. 71(6):e13-e115. [Medline]. [Full Text].