mountain

CLS Student Research Pages

Antimicrobials Avian influenza Blood Substitutes
Cancer Antigen Tests Cord Blood Uses Diabetes
Molecular Genetic Tests Parisitology Stem Cells

Diabetes

April 17, 2009

Shauna Dance


Diabetes

Type I Diabetes

Type I diabetes is a genetic based condition that commonly presents in children and young adults. It is characterized by the failure of the pancreas to make insulin. Without insulin, the body is not able to take up glucose into its cells to fuel the body. The sugar ingested stays in the circulating blood. Those diagnosed with Type I diabetes must take insulin shots with every meal. This is necessary to remove the sugar from the blood and avoid complications. As with any type of diabetes the outcome is controllable with good lifestyle choices.

It is easy for those with Type I diabetes to become hyperglycemic (too much sugar) or hypoglycemic (not enough sugar) very quickly. This makes daily sugar monitoring necessary for these individuals. They are required to test their sugar throughout the day, before meals and after to keep those values in the correct range. If the sugars and too high, they must inject themselves with insulin and if those numbers and too low, ingest sugar to bring them into a safe range.

Insulin resistance (pre-diabetes)

insulin resistant

Insulin resistance is a condition that presents before and increases the risk of developing Type II diabetes. This condition is not present before presentation of Type I diabetes. This condition presents when the body stops responding to insulin produced by the pancreas, this is followed by an increase in blood glucose. The pancreas continues to produce insulin but that insulin is not able to cause sugar uptake. As a result, more insulin is produced, taxing the pancreas. Long term consequences include failure of the pancreas due to over-production of insulin. Cells require insulin to aid in the uptake of sugar from the blood. Without the action of insulin, blood glucose levels rise, and in the long run, lead to Type II diabetes.

There are many reasons that insulin can stop acting on the cells of the body but it is difficult if no impossible to diagnose the reason in each patient. Research has not reach a level where the actual point of defect in the action of insulin or the cell’s receptors can be identified on an individual basis. Advancement in this area of research would provide answers and possibly advancements in the treatment of Type II diabetes.

The cause of insulin resistance and ultimately Type II diabetes comes from 2 sources, genetics, and lifestyle. Genetics sets the stage for the disease but lifestyle controls the outcome.

Type II Diabetesexercise

Type II diabetes develops after insulin resistance and is characterized by high blood sugar levels and a lack of sensitivity to insulin or insufficient production of insulin. This is the most common form of diabetes with the American Diabetes Association1 putting the number at 90-95% of diabetics.

It is possible (but unlikely) that Type II diabetics will develop hypoglycemia; however, hyperglycemia is a constant concern. Providers may ask their patients to monitor their blood sugars daily to control this problem if they feel that is necessary. Good exercise and diet are very important habits for those with both insulin resistance and type II diabetes to implement in their daily lives. These habits can help patients control their condition and improve their lab values and lifestyle.

Lab Tests

A1C (glycated hemoglobin or HbA1c)

The A1C test is a measure of the average blood glucose levels of a patient over the last 3 months. Sugar circulating though the blood system that is unable to be taken up by the cells of the body attaches themselves, or glycates, to the hemoglobin in circulating red blood cells. Because the average life span of the red blood cell is 120 days, the amount of sugar attached to the cell is a picture of the amount of sugar circulating in the blood for 120 days. By no means should the A1C replace daily sugar testing, however, adding this tool to the monitoring of patient cases can greatly improve outcome

In healthy individuals without diabetes, 5% is the average amount of glycated hemoglobin in circulation. A diabetic with long-term, uncontrolled diabetes can have as much as 25% glycated hemoglobin. The acceptable percentage for each patient is different based on age and history but the general rule is to keep the number below 7%. The chart below illustrates what each A1C result means in terms of average daily blood glucose2:

Average Plasma Blood Glucose

A1C Result

100 mg/dL

5%

135 mg/dL

6%

170 mg/dL

7%

205 mg/dL

8%

240 mg/dL

9%

275 mg/dL

10%

310 mg/dL

11%

345 mg/dL

12%

This test is a long term picture of patient blood sugars, as opposed to daily sugar monitoring which is very short term and ever changing. This test also offers an advantage over oral glucose tests for this reason as well. The A1C test can also be a more accurate predictor because it is an average. Most patients have good days as well as bad days. This test avoids “bad day” or “good day” false results. Because the average person’s blood sugars do fluctuate, this test allows for that and reports an average, allowing the physician to better plan the patient’s future regimen. This test can be used for monitoring Type I and Type II diabetes as well as those patients with insulin resistance.

This test can be confusing to patients used to seeing their diabetes values reported in milligrams/deciliter or mmols/liter. This test is reported as a percentage. The ADA1 reports suggestions to make the A1C value made 1 unit used worldwide, though this unit has not been named. This could lead to even more confusion by both patients and providers alike. This test is also limited in that it is not usable as a diurnal measurement. This test can paint a picture of where the sugars have been in the past but do not help the patient improve their sugars on a daily or even weekly basis.

Author Roger Mazzie et al.3 argue that “…without diurnal glucose profiles the clinical and biological relevance of HbA1c or related summary measures are insufficient for clinical decision making.” They are arguing that the HbA1c is useless in planning, diagnosing or stating the prognosis of patients. It is a picture of the past, not the present. It is difficult to plan the future without present data which the HbA1c does not give.

Another criticism of the A1C measurements is that there is too much variability in RBC lifespan to gain a reliable measurement. Research done by Robert M. Cohen et al.4 focuses on this very problem. In their paper they state, “If in reality some life spans were 90 and other 120 days, then this would be responsible for a variation of 25-30% in HbA1c which could be mistakenly attributed to differences in glycemic control.” This means that one diabetic patient may have a relatively high A1C simply because at the time of measurement, he had a high percentage of glycol Ted, old red blood cells circulating through his body. At another time of measurement, a conversely good A1c level may be due to the fact that they have a large percentage of young, new red blood cells circulating in the blood stream that have not had time to become associated with blood sugars. This idea brings into question how accurate the A1C really is.

Oral Glucose Tolerance Test

The oral glucose tolerance test (OGTT) is done to measure how quickly sugar is cleared from the blood stream. This test is done on those with Insulin Resistance and Type II diabetes. Because both of these diseases are characterized by a desensitization of the body’s tissues (muscle, adipose) to insulin, it becomes necessary to measure HOW desensitized the tissues are. This test is designed to measure how quickly blood sugar is removed from the blood stream. When the patient comes in for this test, they must be fasting (without food or beverage other than water) for 8-10 hours. A baseline blood sample is drawn and analyzed to see what the fasting blood sugar level is. The patient is then given a glucose load or a drink containing a measured amount of glucose. They must drink it within a certain time frame to cause sufficient loading of the blood stream with sugar. A blood sample is then drawn every half hour for 2 hours. The amount of sugar cleared from the blood stream at specific set intervals is shown.

The OGTT is a sure fire way of measuring what insulin resistant patients and Type II diabetics struggle with, sugar uptake from the blood. This test is a very tried and true test (though controversial) and used frequently by practitioners for this reason. The OGTT is very sensitive for measuring early Type II diabetes.

The OGTT is a controversial test, according to the text book, Fundamentals of Clinical Chemistry by Tietz9, for the reason that it is affected by a great number of factors causing reproducibility or the ability to get the same numbers more that once, poor. The OGTT is also non-diagnostic or it cannot be used to actually diagnose Type II diabetes or insulin resistance. The numbers resulting from this test better identifies a patient’s risk for developing complications from insulin resistance and Type II diabetes. Several factors can play into the numbers resulting from this test. Whether the patient has been truly fasting, their posture, activity, anxiety, and the time of day are some factors. The drink given to patients to load the blood stream can also be very unpleasant for them to take. It can have a bad flavor, they may not finish it all, or they may feel ill afterwards. Also, multiple blood draws are required in a small time frame. A minimum of 4 venipunctures are required for the test. This can be very uncomfortable for many patients. It can be painful, bruising may occur, and patients may be bothered by the amount of blood taken from them.

Fasting Plasma Glucose Concentration

Fasting plasma glucose concentration is the most commonly used diagnostic test for diagnosing diabetes. A concentration of >126mg/dL is diagnostic of diabetes. This test is done on plasma.This test is done on one tube of plasma. This reduces the amount of blood required from the patient. This test is also diagnostic of diabetes. OGTT cannot be used as a diagnosis of diabetes due to its inability to be reproduced. It is too variable and there are too many factors present that can alter the outcome. This test is very reproducible and does not have many factors to affect the results. The patient does not have to be fasting for this test. Because this test is simpler, it is much easier to get patient compliance.

While this test is used to diagnose diabetes, it takes multiple measurements over time to confirm this diagnosis. This test can also be controversial in the sense that many believe that hyperglycemia or the state of having high blood sugars is a “late” sign of diabetes and that much earlier signs must be detected. This makes this test seem a little bit irrelevant, and simply a confirmatory test for diabetes.

Treatment Research

Bacterial Protection against Type 1 Diabetes5

At the University of Chicago and Yale University, there is research into prevention of Type 1 diabetes in mice. These mice are raised in a germ-free environment, are deficient in innate or natural immunity and are non-obese. The mode of prevention is treating the non-obese mice with a dose of common stomach bacteria that they are not able to naturally develop due to an absence of necessity to develop natural immune defenses in their “hygienic” atmosphere. Because the mice are raised in a germ-free environment, they develop without a natural or innate immune system. After treatment with friendly stomach microbes, which would be developed in a free-living mouse, they appear to become immune to developing the auto-immune disease of Type I diabetes. When these mice were raised in a germ-free environment (no natural immunity developed) and were never given the treatments of the normal stomach microbes, these mice developed severe diabetes.

This suggests that the “innate” or “natural” immune response in these mice under normal circumstances, may lead to the development and onset of Type I diabetes.

This article clearly gives hope to an understanding of the development of Type I diabetes. We do know that this disease is autoimmune, now we must understand what triggers the disease and what can be done to prevent onset. While this is only baby steps to understanding, it shows that Type I diabetes may one day be manipulated and controlled in humans.

This study by no means shows giant bounds of new understanding of Type 1 diabetes or any other autoimmune disease. This data requires rigorous and lengthy testing to cement these ideas and to find the next steps in understanding Type I diabetes onset.

Fetuin-A Levels6

Fetuin-A is a protein found in the blood that is produced by the liver. There is a question whether this protein is correlated with causing the development of Type II diabetes, especially in older people. Fetuin-A is secreted by the liver and binds to insulin receptors in muscle and fat around the body. This prevents insulin from binding at those sites. Because it is necessary for insulin to bind to these sites to cause the removal of sugar from the bloodstream, inhibition of those sites causes higher levels of sugar to remain in the blood, leading to insulin resistance and Type II diabetes. The physician conducting this study, Joachim Ix, MD., followed a group of older participants over six years. These patients were originally non-diabetic. Over the course of six years, body measurements (weight, waist circumference, etc.) were taken and annual plasma glucose measurements and fetuin-A level were done. Dr. Ix found at the end of the study that there was a positive correlation between the development of diabetes, and severity, and levels of fetuin-A levels.

This study provides another analyte that may be studied and measured to determine risk, and development of diabetes. This analyte may also prove to be a way of decreasing the onset and severity of diabetes. If the production and secretion of fetuin-A can be controlled, or lessened, insulin will not have to compete for binding sites, allowing sugar to be cleared from the blood.

This study was only performed in an elderly population. The trend of Type II diabetes is spreading to a younger and more diverse population every year. Many more questions can be asked and tested with fetuin-A. Is this only increased in the elderly? Are the same trends seen in younger populations? The goal of diabetes treatment needs to be focused on detection and prevention. Learning what fetuin-A’s role is in young people would answer more questions about the development of Type II diabetes.

Deuterated Oral Glucose Tolerance Test (2H-GTT)15

Insulin resistance and Type 2 diabetes can be characterized by the desensitization of body tissues, such as muscle tissue, to the effects of insulin. In the past, no test has been a good indicator of insulin resistance or pre-diabetes. Early detection allows practitioners and patients time to counteract or change lifestyle habits that can lead to a positive outcome in diabetes patients.

This test, performed in vivo (within the patient), is based on the oral glucose test and tests the body’s glucose clearing abilities based on the release of deuterium from oral 2H-glucose to body water. This test can be measured from saliva or plasma. The test is measured by isotope ratio mass-spectrometry or cycloidal MS.

This test follows the physiology of insulin pathways which are already known. This test is inexpensive and an out-patient procedure. The test is also non-invasive; simple oral administration and saliva tests are the simplest ways of measurement. At most, the patient is subjected to a venipuncture.

If further research deems this test viable, this test will be an excellent tool for measuring the effects of insulin-sensitizing medications. Practitioners will be able to see exactly how much more insulin can be taken up by the tissues when those medications are added to a patient’s regimen.

This test is new and requires testing and research before it can become a mainstream diabetes diagnostic tool. While this test is very similar to a common test already used, the oral glucose tolerance test (OGTT), it may require extra patient education. Many patients have monitored their insulin resistance for long periods of time and are used to the common methods. Change is sometimes hard for patients and this test would make them learn new values and methods which can be burdensome to some.

Research must also go into the effects of this test paired with insulin-sensitizing agents. At present this is not know. It is necessary to understand how those medications react with the deuterium, if they do at all.

[18F]-Fluorethoxy-Repaglinide7

The pancreas, paired with the liver are the major organs involved with blood sugar regulation. The pancreas makes and secrets insulin, which then binds to cells, allowing them to become sensitive, and able to take up glucose from the blood. In the pancreas the insulin, along with many other hormones, is made and secreted by the islets of Langerhans. These islets are very involved in both type I and type II diabetes. In type I diabetes these cells can be destroyed (autoimmune) resulting in a complete stop in the production of insulin. In type II diabetes these cells produce insulin at high rates in response to the high levels of sugar in the blood; as long as there is sugar in the blood, these cells try to produce more and more insulin. After so long these cells begin to show a decrease in their ability to continue producing insulin at a high rate and can eventually stop producing insulin. It is important for practitioners to be able to test and measure how many islets are present and working in diabetic patients. It gives them a picture of their patient’s ability to produce insulin so they can then adjust the patient’s treatment. Imaging and testing islet mass in-vivo, however, is difficult; this is because no islet cell tracers have been developed.

IsletResearch is being done to evaluate the ligand, [18F]-fluorethoxy-repaglinide as a tracer for measuring islet mass. This ligand is of interest because it has a very high affinity for the sulfonylurea receptor SUR1. This receptor is a membrane protein which regulates the secretion of insulin. The ligand is injected by IV and the highest level of tracer activity has shown to occur 5 minutes after injection. This test has only been done in mice and has yet to be tested in humans.

See CLS Stem Cells Page that describes regrowth of Insulin Producing cells

Detection of Altered Gluconeogenesis8

When the cells in the body do not receive glucose, the liver is stimulated to convert stored glucagon to glucose (gluconeogenesis) and release it into the blood. When the cells are lacking sugar due to impairment in cell uptake of blood glucose, this release of glucose by the liver elevates blood sugars. This occurrence is difficult to control and it can lead to obesity, insulin resistance, and diabetes. Being able to measure the rate of gluconeogenesis and ultimately how fast sugar is being dumped into the blood is a tool practitioners can use to diagnose, monitor and treat their patients. It is another facet of information that can improve patient health.

Methods used up to this point require tracers to be injected into patients, which take several hours to implement and get results from. There is no method that can give an immediate reading. Quick reads of gluconeogenesis could be helpful in emergency situations when diabetic patients are in a crisis such as ketoacidosis or heart failure.NMR

Current research is investigating the use of NMR and hyperpolarized 13C pyruvate as a tracer to detect gluconeogenesis quickly. NMR allows real-time visualization of the tracer binding with hepatic metabolites. This can occur as quickly as 90 seconds. This method also allows for use of multiple tracers, without interference between them but NMR is very limited in sensitivity.


 


Diabetes Monitoring Research

Much research is done to find new ways for patients to monitor their blood sugars on a daily basis, in a non-invasive or minimally-invasive manner. The current method of monitoring blood glucose is termed invasive and involves extracting blood multiple times a day. Non or minimally invasive ways of monitoring do not require blood. Finding a method for patients to use on a daily basis that decreases the amount of blood or the need for blood can help patients feel less pain and feel less hampered by their daily routine of blood testing. Research is always looking for ways of blood monitoring that is less complicated and less variable. With the current monitoring system, there are many variables that can give the patients incorrect result. This can lead to a mistake in insulin dosing or sugar intake. Those variables can include: inadequate blood drop, unclean testing surface, interstitial fluid contamination, etc. Patients having to use lancets can cut themselves deeply, causing excessive bleeding and pain. They can also inadequately cut, requiring additional incisions. Finding new ways to monitor blood sugars focuses on improving patient lifestyle and accuracy. The following research compares a broad spectrum of new body sites, fluids, and methods of obtaining blood sugar readings.

Ultrasonically extracted interstitial fluid10

Using Body metabolism as a glucose monitor 11


Photonic CrystalGlucose-Sensing in Tear Fluid12


Trans-Cutaneous Fluorescence13

Exhaled Volatile Organic Compounds14

Related Links


References

1. American Diabetes Association. http://www.diabetes.org//diabetes-research/summaries/nathan-what-a1c-level-means.jsp. February 2, 2009.

2. Accu-chek. http://www.accu-chek.com/us/rewrite/content/en_US/4.1.2.2:20/article/ACCM_general_article_2427.htm&ic_campID=26?gclid=CIOThsLnv5gCFQwxawodIBWdYQ&gclid=CIOThsLnv5gCFQwxawodIBWdYQ. February 3, 2009.

3. Mazze, Roger, Ellie Strock, David Wesley, and Robert M. Cuddihy. "Clinical Limitations of the Relationship Among Mean SMBG, CGM and HbA1c." American Diabetes Association. 2008. ADA. 24 Feb. 2009 http://professional.diabetes.org/Abstracts_Display.aspx?TYP=1&CID=68495.

4. Cohen, Robert M., et al. “Red Blood Cell (RBC) Survival Differences Among Hematologically Normal People with Diabetes (DM) Make a Clinically Important Difference in HbA1c.” American Diabetes Association, 2007. ADA 24 Feb 2009. http://professional.diabetes.org/Abstracts_Display.aspx?TYP=1&CID=54055.

5. Yale University (2008, September 22). ‘Friendly’ Bacteria Protect Against Type 1 Diabetes, Researchers Find. Science Daily. Retrieved February 24, 2009, from http://www.sciencedaily.com/releases/2008/09/080921162048.htm.

6. Ix,JH, et al. Health ABC Study. Fetuin-A and incident diabetes mellitus in older persons. Retrieved 2/24/2009. Journal of the American Medical Association. 300(2):182-8, 2008 Jul 9. http://www.diabetes.org/diabetes-research/discoveries/researchers-in-the-news/archive.jsp#ix.

7. Schneider Stephan, et al. American Diabetes Association. [18F]-Fluorethoxy-Repaglinide: A Possible New Ligand for Non-Invasive Estimation of the Pancreatic Islet Cell Mass In-Vivo. Retrieved 2/24/2009 from http://professional.diabetes.org/Abstract_Cisplay.aspx?TYP=1&CID=43918.

8. Merritt, Matthew E., et al. Detection of Altered Hepatic Gluconeogenesis by Nuclear Magnetic Resonance (NMR) and Hyperpolarized 13C Pyruvate. Retrieved 2/24/2009 from http://professional.diabetes.org/Abstracts_Display.aspx?TYP=1&CID=68554.

9. Burtis, Carl A., Edward R. Ashwood, and David E. Bruns. Tietz Fundamentals of Clinical Chemistry. Philadelphia: Saunders, 2007.

10. Mitragotri, Smir, et al. Analysis of ultrasonically extracted interstitial fluid as a predictor of blood glucose levels. Journal of Applied Physiology. Retrieved 2/25/2009 from http://jap.physiology.org/cgi/content/ful/89/3/961.

11. Ko, Jae B., et al. Body Metabolism Provides a Foundation for Noninvasive Blood Glucose Monitoring. Diabetes Care. Retrieved 2/25/2009 from http://care.diabetesjournals.org/cgi/content/full/27/5/1211.

12. Alexeev, Vladimir L., et al. Photonic Crystal Glucose-Sensing Material for Noninvasive Monitoring of Glucose in Tear Fluid. Clinical Chemistry. Retrieved 2/25/2009 from http://www.clinchem.org/cgi/content/full/50/12/2353.

13. Kristensen, Jesper S. Trans-Cutaneous Fluorescence Lifetime Based Continuous Glucose Reading for Long Term Interrogation. American Diabetes Association. Retrieved 2/24/2009 from http://professional.diabetes.org/Abstracts_Display.aspx?TYP=1&CID =52523

14. Galassetti, Pietro, et al. Exhaled Volatile Organic Compounds: Potential Non-Invasive Markers of Plasma Glucose during an Oral Glucose Tolerance Test. American Diabetes Association. Retrieved 2/24/2009 from http://professional.diabetes.org/Abstracts_Display.aspx?TYP=1&CID=44678

15. Murphy, Elizabeth L., et al. A New, Sensitive In Vivo Diagnostic Test of Insulin Resistance: The Deuterated Oral Glucose Tolerance Test (˛H-OGTT). American Diabetes Association. Retrieved 2/24/2009 from http://professional.diabetes.org/Abstracts_Display.aspx?TYP=1&CID=44866