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SGLT2 (sodium-glucose co-transporter-2) is a receptor located primarily in the kidney. SGLT2 acts to reabsorb glucose (sugar) filtered by the kidney into the urine. With the help of SGLT2 receptors, very specialized cells in the kidney (proximal tubular cells) are able to draw sugar out of the urine and back into the bloodstream to be used for energy.
Sugar in the urine (Glucosuria)
Believe it or not, sugar (or glucose) normally enters the urine through the kidneys every day. Approximately 162 grams of sugar are filtered into the urine daily (similar to the amount of sugar in four soda cans). But this does not mean the urine of healthy patients contains sugar. In fact, the body is happiest when all of this sugar is reabsorbed back into the bloodstream. As mentioned above, sugar is reabsorbed and pulled out of the urine with the help of the SGLT receptors.
Approximately 162 grams of sugar are filtered into the urine daily (similar to the amount of sugar in four soda cans).
SGLT2 inhibitors
SGLT2 inhibitors are a class of prescription, oral anti-diabetic medications that that are also called Gliflozins. Inhibitors of SGLT2 bind this receptor and block a portion of sugar reabsorption, causing sugar to spill out into the urine even at normal blood sugar levels. When on an SGLT2 receptor inhibitor, an adult patient will urinate out approximately 70 grams of glucose per day, as compared to non-diabetics who have no sugar in their urine under normal circumstances.
Blood sugar levels and SGLT2 inhibitors
As a result of inhibiting the SGLT2 receptor, the urine sugar increases and blood sugars decrease (both before and after meals). This class of medication is usually associated with a 1% reduction in HbA1c levels.
What are side effects of SGLT2 inhibitors
Humans are not the only organisms that like sugar. When sugar is present in the urine, it is likely to promote the growth of unwanted bacteria and fungus. For this reason, when someone is on an SGLT2 inhibitor, the risk of developing a urinary tract infection or yeast infection increases by about 10%. As sugar and water increase in the urine, patients typically experience an increase in the volume of urination with the potential of lower blood pressure (by about 5 mmHg systolic). If the blood pressure drops too low, this can cause dizziness, especially when standing or getting out of bed. In those patients already on a diuretic or ‘water pill,’ the dose of that medication will likely be decreased or held prior to starting an SGLT2 inhibitor to decrease abnormally low blood pressure (hypotension).
Dosing must be chosen carefully in those patients with kidney problems due to the fact that the SGLT2 inhibitor medications require an intact filtration rate to work properly. Despite what is conveyed on commercials, the risk of diabetic ketoacidosis on an SGLT2 inhibitor is quite low in those with type 2 diabetes: less than 0.1%. These cases were mostly described in patients on SGLT2 inhibitors in the hospital under large amounts of stress, such as going for surgery or a systemic infection called sepsis.
The SGLT2 inhibitors that are currently available in the market are: Invokana® (Canagliflozin), Jardince® (Empagliflozin), and Farxiga® (Dapagliflozin)
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