Diabetes Mellitus

Diabetes Chapter Summary and Credits

Jennifer Kong

Chapter Summary

The endocrine pancreas is mostly comprised of the pancreatic islet cells: alpha (glucagon) and beta (insulin). Insulin and glucagon are involved in glucose homeostasis: a consistent blood sugar level regardless of whether one has eaten or not. In response to high blood glucose levels (e.g. after a meal), insulin is produced by the beta cells to encourage glucose uptake and utilization by tissues. As well, insulin release promotes storage of excess glucose in the storage form glycogen, available for later use (e.g. fasting).

Diabetes mellitus is characterized by high blood glucose levels (hyperglycemia). The cause of the hyperglycemia could be due to either a problem with the production and release of insulin (T1DM) or sensitivity to insulin in all tissues (T2DM and gestational). The common manifestations of diabetes, regardless of the type, is high blood sugar, excessive thirst and urination, fatigue, confused/irritable, and high heart rate.

The cause and risk factors of diabetes is based on the type. Genetics and environmental triggers are thought to be the cause of T1DM, leading to the destruction of insulin-producing beta cells by autoantibodies. T2DM also has a genetic component, but risk factors that suggest an overabundance of circulating nutrients can lead to tissue insensitivity to insulin. In gestational diabetes, pregnancy is the cause as well as risk factors of being pre-diabetic before pregnancy.

Diagnosis is based on tests for blood sugar – whether amount circulating when fasting (fasting blood glucose), after a glucose challenge (oral glucose tolerance test), or after months of high circulating sugars (glycosylated hemoglobin A1C). Urine can also be tested for the presence of glucose which is suggestive of diabetes, but not definitively as diet and kidney disease can also yield urine with sugar. The presence of ketones – common during diabetic ketoacidosis – can be measured in both the blood and urine.

Treatment and management of diabetes depends on the type. T1DM require injectable insulin, daily blood glucose checks, and thoughtful consideration of their diet and activities. T2DM and gestational diabetes can be managed with lifestyle changes to promote insulin sensitivity (e.g. exercise, dietary modifications). Medications can also be used in T2DM/gestational if lifestyle changes is insufficient. Though not as frequent, Type 2 diabetics also require blood glucose monitoring.



Author:  Dr. Jennifer Kong (BCIT & UBC)

Author of questions & editing:  Eva M. Su (UBC undergraduate student)

Medical Illustrator:  Sarah Perkins (UBC-O undergraduate student)

Histopathology video:  Dr. Jennifer Kong (BCIT & UBC) with guidance from Dr. Gang Wang (UBC)

Patient narratives:  Sally, Bill, & Katie McKinstry

Videoeditor:  Chris Cambon (BCIT)




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Pathology Copyright © 2022 by Jennifer Kong is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License, except where otherwise noted.

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