Defective Glucose and Water Transport in Two Forms of Diabetes (Part 2 of 3)

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Did you know that there is another type of diabetes? It is not related to sugar but with the function of water retention by the kidney.

Here is the second part of my report concerning about diabetes.

Defective Glucose and Water Transport in Two Forms of Diabetes (Part 2 of 3)

Diabetes Insipidus

Diabetes insipidus is similar to diabetes mellitus. Instead of glucose, it is all about the re-absorption of water from the urine to the bloodstream. The hormone responsible for this condition is the vasopressin produced in the pituitary gland (Felman).

Instead of the GLUT4, aquaporin is present in the collecting duct in the kidney. These are responsible for the absorption and re-absorption of water.

The aquaporins 3 and 4 (AQP3 and AQP4, respectively) are located in the basolateral membrane of the urine-collecting duct in the kidney. Aside from AQP3 and AQP4, there is aquaporin AQP2 that will attach itself to the apical membrane where the diluted urine flows. This only happens when the arginine-vasopressin (AVP) binds with its receptor. The G protein, Gs, produces adenyl cyclase and converts ATP to cAMP. AQP2 will be phosphorylated by the protein kinase A (PKA). The phosphorylated AQP2 (P-AQP2) will attach itself to the apical membrane and facilitate the reabsorption of water going back to the bloodstream. The final product will be concentrated urine (Qureshi, et al).

Like type 1 and type 2 diabetes mellitus, when there is a problem in the supply or the body’s reaction to vasopressin, diabetes insipidus arises.

There are 2 major types of diabetes insipidus – neurogenic or the central type, and the nephrogenic or renal type. Like diabetes mellitus, pregnant women may also suffer diabetes insipidus and this iscalled the gestogenic diabetes insipidus (“Diabetes Insipidus and Diabetes Mellitus”).

Figure 3 illustrates how water reabsorption in the body occurs.

The central type of diabetes insipidus is where little or not enough amounts of the antidiuretic hormone vasopressin are secreted from the pituitary gland. Because of this, there will be no substance to be attached to the AVPR2 receptor that is supposed to give the signal to the AQP2 to do its job. On the other hand, the renal type diabetes insipidus have enough amount of vasopressin but the body tends to have resistance in binding with the said hormone to facilitate the movement of the AQP2 to the apical membrane of the collecting duct cell in the kidney for the reabsorption of water from the urine (Qureshi, et al).

The third type, but considered to be rare, is the gestogenic diabetes insipidus. One of the side effects of the chemical reaction of the placenta in the body is the destruction of the vasopressin hormone. The degradation of the vasopressin is done by the vasopressinase or cysteine aminopeptidase. This usually occurs between the third trimester of pregnancy to the early postpartum period (Felman).

Diabetes is often related to blood sugar with the early signs or symptoms of excessive urination. However, there are two forms of diabetes – diabetes mellitus and diabetes insipidus. The urine in diabetes mellitus is sweet while in diabetes insipidus is very dilute or tasteless.

Both forms of diabetes are hormone-related. Insulin is secreted by the pancreas for diabetes mellitus while vasopressin is secreted by the pituitary glands for diabetes insipidus.

Diabetes prevalence in the Philippines is quite alarming. This only gives us the warning to keep our health monitored and choose a lifestyle that will keep us fit.

References:

Baclig, Cristina Eloisa. “Diabetes: A Bitter Health Crisis for Filipinos.” INQUIRER.Net, 21 July 2021, newsinfo.inquirer.net/1461980/diabetes-a-bitter-health-crisis-for-filipinos.

Bryant, Nia J., et al. “Regulated Transport of the Glucose Transporter GLUT4.” Nature Reviews Molecular Cell Biology, vol. 3, no. 4, 2002, pp. 267–77. Crossref, https://doi.org/10.1038/nrm782.

 

“Diabetes Insipidus and Diabetes Mellitus.” The Diabetic Voice.Com, www.the-diabetic-voice.com/diabetes-insipidus-and-diabetes-mellitus.html. Accessed 26 Apr. 2022.

 

Felman, Adam. “What’s to Know about Diabetes Insipidus?” Medical News Today, 7 Apr. 2022, www.medicalnewstoday.com/articles/183251.

 

“Glucose Regulation and Utilization in the Body.” Nutrition FN 225, media.lanecc.edu/users/powellt/FN225OER/Carbohydrates/FN225Carbohydrates5.html. Accessed 26 Apr. 2022.

 

“Insulin | Definition, Structure, and Function.” Encyclopedia Britannica, www.britanica.com/science/insulin.

 

Nelson, David. Lehninger Principles of Biochemistry. 7th ed., W.H. Freeman, 2017.

 

Qureshi, Sana, et al. “Diabetes Insipidus: Celebrating a Century of Vasopressin Therapy.” Endocrinology, vol. 155, no. 12, 2014, pp. 4605–21. Crossref, https://doi.org/10.1210/en.2014-1385.

 

Tahrani, Abd A., et al. “Management of Type 2 Diabetes: New and Future Developments in Treatment.” The Lancet, vol. 378, no. 9786, 2011, pp. 182–97. Crossref, https://doi.org/10.1016/s0140-6736(11)60207-9.

 

Vasiljević, Jovana, et al. “The Making of Insulin in Health and Disease.” Diabetologia, vol. 63, no. 10, 2020, pp. 1981–89. Crossref, https://doi.org/10.1007/s00125-020-05192-7.

 

“What Is Diabetes?” Centers for Disease Control and Prevention, 2 Mar. 2022, www.cdc.gov/diabetes/basics/diabetes.html.