Understanding Diabetes: The Basics of Blood Glucose

Written by Robert Ehrman, MD and Reviewed by Johanna Burani RD, CDE

Have you been told you have diabetes? Does someone in your family take medicine for high blood glucose? Do you have a friend who has been told they have pre-diabetes? For many people, the answer to at least one of these questions is “yes.”

But what does “having diabetes” mean? Why do some people take pills for their diabetes and others have to take insulin with a shot  injections? These are great questions!

It can seem like there are too many things to know and understand about diabetes. But, learning just a few basic facts about how diabetes can help you understand and manage it much better.

What is Glucose and How Does Your Body Use It?

causes of heart diseaseGlucose is a type of sugar. Other types of sugar include fructose, sucrose, and lactose. Glucose is special because it is the sugar your body likes to use for fuel. When you eat, your stomach and intestines break down what you ate into the basic building blocks of food: fat, protein, and sugar. These building blocks then go from the intestines into the blood stream.

The cells in your body need the glucose for energy. But the glucose can’t get into the cells by itself: it needs help! This is where insulin comes in—it is the helper that lets the glucose get from the bloodstream into the cells.

The Problem in Diabetes is Insulin!

The cells in your body run on glucose. And for that glucose to get into the cells, insulin is needed. So what happens if there is no insulin or not enough insulin in your body? No insulin means that glucose can’t get into the cells, so it stays in the bloodstream. Too much glucose in the bloodstream is also called “high blood glucose.” And this is exactly what diabetes is—blood glucose levels that are too high!

Where Does Insulin Come From and Why Does it Stop Working?

Insulin is made in cells in the pancreas called “beta cells.” These cells get messages from other parts of the body that tell them when more insulin is needed, such as after you eat a meal. You do need insulin all the time, not just after you eat. In between meals, the beta cells put just enough insulin into the blood stream to keep your blood glucose level in the normal range.

The problem in diabetes is that the beta cells either don’t make any or enough insulin, or the insulin they do make doesn’t work properly in the body. This is the major difference between type 1 and type 2 diabetes.

Type 1 Diabetes

In type 1 diabetes, the beta cells in the pancreas are accidentally destroyed by the person’s immune system. The immune system is the part of the body that fights off diseases like the flu. When it accidentally attacks a normal part of the body, it is called an “auto-immune disease.” Other auto-immune diseases you might know about are Lupus, Grave’s Disease or Celiac Disease.

When the beta cells are destroyed, the body can’t make any insulin. This means that people with type 1 diabetes must give themselves insulin shots. This type of diabetes is usually discovered in childhood, but sometimes not until a person is in their 20’s or 30s.

Type 2 Diabetes

In type 2 diabetes, there are two problems. The first is that the beta cells do not produce enough insulin to meet the body’s needs. Doctors don’t know exactly why this happens, but it is probably due to many things like age, family history, and other medical problems.

The second problem in type 2 diabetes is that the cells in your body don’t use the insulin that your body makes in quite the right way. This is called “insulin resistance.” Again, doctors aren’t exactly sure why this happens, but they think it has something to do with family history and being overweight.

This type of diabetes is usually a disease you get when you’re an adult. However, as more children become overweight and obese, it is being seen more often in younger children and teenagers.

Type 2 diabetes can be treated in a few ways. You might start out taking pills that increase the amount of insulin your pancreas makes. Or, you might take a pill that helps the cells in your body improve at using the insulin that’s already there.

If you have type 2 diabetes, over time, your beta cells may stop making any insulin. If this happens, you will need to start taking insulin shots. Everyone’s body is different, so this doesn’t happen to everyone with type 2 diabetes. And if it does happen to you, that doesn’t mean your diabetes is worse, or that you didn’t do a good job of taking care of yourself.

Take Home Points

  • diabetes-basics-blood-glucoseThe cells in your body need glucose for energy
  • Glucose comes from carbohydrates and the protein foods you eat
  • Once glucose is in the blood, insulin is needed to get it inside the cells where it can be used for fuel
  • In type 1 diabetes, the cells that make insulin are destroyed and the body doesn’t make any insulin
  • Type 1 diabetes is always treated with insulin shots
  • In type 2 diabetes, your body doesn’t make enough insulin and the cells in the body can’t use it properly
  • Type 2 diabetes is treated with pills or with insulin shots, and sometime both!



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Constance Brown-Riggs, MSEd, RD, CDE, CDN—an award-winning RD, certified diabetes educator, and past national spokesperson for the Academy of Nutrition and Dietetics, is the author of The African American Guide to Living Well With Diabetes, which received the Favorably Reviewed designation from the American Association of Diabetes Educators, and Eating Soulfully and Healthfully with Diabetes.

Dr. Lori Shemek, PhD, CNC, CLC, the best-selling author of “Fire-Up Your Fat Burn! and leading health and weight loss expert, is also known as “The Inflammation Terminator.” She has made it her mission to educate the public on the toxic effects of certain foods and lifestyle choices and how they create inflammation in the body. She is a leading authority on inflammation and its role in weight loss, preventing disease and optimizing health.

Rebecca Bitzer – MS, RD/LD, CEDRD is an award-winning Registered Dietitian, writer, speaker, blogger, and REBEL Dietitian business owner. Rebecca and her team of six Registered Dietitians have counseled thousands of clients struggling with diabetes for over twenty-five years. They work closely with each other along with internists, endocrinologists, therapists, and families.

Maureen Sullivan – RN, CDE has worked for many years as a Registered Nurse, most of them in emergency and trauma services. She is a Certified Emergency Nurse, Certified Diabetes Educator, and the former manager of a hospital stroke program. Maureen’s wealth of knowledge, passion for nursing and education, and ability to engage people makes her an excellent teacher and a captivating lecturer. Recently, Maureen has been concentrating on writing, speaking and teaching, as well as working on her award-winning weekly podcast, “The Health and Humor Show.”

Lauren Harris-Pincus, MS, RDN is a nutrition communications specialist, registered dietitian in private practice, social media consultant, speaker, spokesperson and corporate consultant. She is currently the owner of Nutrition Starring YOU, LLC and www.NutritionStarringYOU.com. Lauren strongly believes that we should “Think Healthy, not Skinny”, and “EveryBODY is unique, your diet should be too”. Lauren was co-host of the Family Food Experts Kitchen radio show, available for listening on iHeart Radio and iTunes. Also known as one of the “NutritionBabes”, Lauren co-founded NutritionBabes.com, a popular Health and Wellness website in 2009. NutritionBabes.com was voted one of Healthline’s Top 100 Health Blogs in 2011, 2012 and 2013.

Mark Heyman, PhD, CDE is a clinical health psychologist and the director of the Center for Diabetes and Mental Health (CDMH). In addition to treating patients with type 1 and type 2 diabetes, Dr. Heyman provides training for health care providers on how to identify and address the emotional and behavioral aspects of diabetes in their patients. He also works with pharmaceutical and medical device companies to help them understand these issues and incorporate this information into their sales, marketing, and patient education materials. He is particularly interested in empirically supported behavioral interventions that promote behavior change and improve physical and mental health in people with diabetes.

Katie Ferraro, MPH, RD, CDE is a nationally-recognized registered dietitian, certified diabetes educator and author with an expertise in nutrition communications and curriculum development. She is the co-author of “Diet Therapy in Advanced Practice Nursing” (McGraw Hill, 2014) and an Assistant Clinical Professor of Nutrition at the University of California San Francisco and University of San Diego’s graduate schools of nursing.

Dr. Beverly S. Adler, PhD, CDE (aka “Dr. Bev”) is a clinical psychologist and certified diabetes educator, author and speaker. She specializes treating the emotional issues of people with diabetes. In her private practice, she provides individual, family and/or group therapy utilizing a cognitive behavior therapy orientation, combined with a spiritual approach. Her goal is to empower her patients to manage their diabetes.

Dr. Bev is the author of two self-help diabetes books. She has written numerous articles which are published in print and online – always focused on diabetes from the emotional perspective. She also speaks to audiences of people living with diabetes, as well as, to audiences of healthcare professionals and diabetes educators. Dr. Bev, herself, has been living successfully with type 1 diabetes for 40+ years.

In August 2016, Dr. Bev was honored to receive the “CDE Entrepreneur of the Year” Award from her Metropolitan NY Association of Diabetes Educators.

Jill Weisenberger, MS, RDN, CDE, FAND is an internationally recognized nutrition and diabetes expert with more than two decades experience. Through writing, speaking and one-on-one coaching, Jill empowers people to grab control of their health. She has worked as both a nutrition counselor and a diabetes educator in the hospital and research settings, and now in private practice in Newport News, VA. Jill is known for her practical approach and caring attitude. Her no-nonsense strategies to eating well include foods that both taste good and are good for you.

Marlene Koch (pronounced ‘cook’) is a nationally recognized nutritionist, popular TV personality and New York Times bestselling author. She graduated Magna Cum Laude from UCLA with a Bachelor’s degree in Nutritional Science. She is a registered dietitian and one of a select group of dietitians to hold an advanced certificate in Child and Adolescent Weight Management from the Academy of Nutrition & Dietetics.

Marlene has taught professional chefs from the American Culinary Federation the principles of healthy cooking and eating. She has been adjunct Nutrition professor and cooking instructor for Columbus State College and the Columbus State Culinary Academy, and she is a nationally recognized expert in weight loss, diabetes, child and adolescent nutrition, and sugar substitutes.

Marlene has sold over one million cookbooks, and is a regular guest on QVC.

Barbara Ruhs – MS, RDN is a Registered Dietitian Nutritionist and owner of Neighborhood Nutrition LLC, a consulting firm focused on providing solutions to help food companies and supermarkets improve consumer health & wellness. She’s a former supermarket dietitian and has run a successful business for 17 years. A leader in the field of nutrition, her mission is to help people by impacting the way food is produced, marketed and sold. She’s a strong advocate for supermarket dietitians and believes the retail food industry has the greatest potential to impact public health.

Cheryl Orlansky has over 25 years of experience in health promotion and chronic disease prevention and management. Her first career as a registered dental hygienist led her towards a path of wellness and nutrition! Her expertise is in diabetes, weight management and cardiovascular disease for individuals and groups. She works in a large private practice including endocrinology, internal medicine, rheumatology, neurology and sleep medicine. She is an award winning dietitian with current leadership positions in state and local dietetics organizations.

She has been interviewed and quoted in media outlets for WebMD, Atlanta Sports and Fitness, Georgia Public Broadcasting, and the Atlanta Journal and Constitution. She has partnered with V-103 Radio to lead supermarket tours as part of a community outreach during National Nutrition Month.

Cheryl helps her clients reach balance through lifestyle choices: cooking and eating, activity and purpose in life.

Jackie Newgent, RDN, CDN, is a registered dietitian nutritionist and classically-trained chef. With a passion for helping people (including her father) with diabetes, she’s author of The With or Without Meat Cookbook: The Flexible Approach to Flavorful Diabetes Cooking and the award-winning The All‐Natural Diabetes Cookbook, both published by the American Diabetes Association. Jackie is also author of 1,000 Low-Calorie Recipes and Big Green Cookbook. Her next book, The All-Natural Diabetes Cookbook—2nd Edition, was published in 2015.

Nutritionist Rania Batayneh, MPH is the author of the best-selling book, The One One One Diet. She holds a master’s degree in public health nutrition from the University of Michigan School of Public Health and is also a Wellcoaches Certified Health and Wellness Coach endorsed by the American College of Sports Medicine (ACSM).

OmnichannelHealth Media, publisher of DiabetesDigest.com, does not provide medical advice, diagnosis or treatment. See additional information.