Nutrition Essentials: Carbohydrates and Protein

Nutrition is an integral part of any management plan for diabetes. Yet, there is no such thing as a diabetic diet, per se. However, if you are concerned about your weight because it might have contributed to diabetes or you want to control the impact of food on your blood glucose levels, you do need to consider your overall eating habits and type of nutritional intake. You can start, therefore, by evaluating your sources for two of the major components of any diet: carbohydrates and protein.

What are Carbohydrates?

Carbohydrates are one of the components of food. They are typically found in the form of sugars and starches.  The sources for carbohydrates are both plant and animal. Chemically, the structure is formed from various combinations of oxygen, hydrogen and carbon – hence the name.

Carbohydrates in the form of fundamental sugars are classified in accordance to the number of molecules linked together[1]. As a result you have:

  • Monosaccharide –referring to a single molecule. These are simple sugars. The 2 most common examples are glucose (derived from starch) and fructose (derived from fruit or cane sugar).
  • Oligosaccharides – this type has from 2 to 10 monosaccharide molecules
  • Disaccharide – reference to the presence of two molecules that may or may not be formed from the same monosaccharides. This group of sugars contains sucrose, lactose and maltose
  • Polysaccharide – indicating more than 2 molecules. They can have more than 10 in a chain. Members of this sugar group are starch, glycogen and cellulose

Why the Focus on Carbohydrates?

When food is digested, all carbohydrates are condensed to a single molecule – a monosaccharide. This is to permit absorption in the small intestine for release into the bloodstream. After the absorption, “single sugar” monosaccharides in the bloodstream stimulate the release of insulin which facilitates the cell uptake, cell use and glucose storage activities. Some of the excess sugar is transported to the liver.

A healthy liver generally releases enough glucose into the blood stream to maintain a circulating blood sugar level of around 90 mg/dl (5 mmol/liter). Any glucose above this amount remains stored in the liver and converted by insulin action into polysaccharide glycogen. The liver can, however, only store at the uppermost about 90 gm of glycogen. Some glucose is stored in the muscles which are capable of storing 300 gm.[2]

If the uppermost amount of stored glycogen is reached in the liver, the remaining or excess glucose enters a process of fatty acids synthesis. The fatty acids are exported out of the liver as lipoproteins. The fatty acids are broken down and triglycerides are formed. Triglycerides are stored in the adipocytes or fat cells. In other words, glucose enters muscle, fat and other tissue cells where it is used or stored. Insulin action is what triggers the uptake of glucose by particular cells other than in the liver and the brain. The liver is not insulin dependent for cell uptake but it does use insulin for glycogen synthesis.

Glucose is employed in a number of functions which makes it extremely important in anyone’s diet. It helps in the manufacture of ATP in the mitochondria which is needed for chemical energy transport. It is readily available for rapid oxidation and quick energy conversion. In these roles, it is by far the favorite source for high energy expenders. In the central nervous system, energy is in constant demand, and thus, glucose is of vital importance.

To sum it up succinctly, carbohydrates are preferred by your body for several reasons. Carbohydrates are broken down into glucose, which is the primary engery source for the body to function. Glucose is transported by the blood stream. In order for your body to utilize the glucose for energy, it releases insulin. Without insulin, most of your glucose would remain in your blood stream and never be utilized.

This is a short explanation for an amazing but complex physical process. However, it explains why diabetics must manage their carbohydrate consumption. This component of food raises the blood sugar level following a meal. While research indicates both the amount and type of carbohydrates affect your blood glucose, it appears to be the amount that has a greater effect.[3] If you want to keep your blood sugars at the right levels, you need to consider the amount of carbohydrates you eat. If you are diabetic, you, in all likelihood, will have to adjust your amount and type in order to meet your blood sugar targets.

Recommendations for Carbohydrate Intake

The amount of carbohydrates you ingest should reflect several factors. These include:

  • Age or stage of life – e.g. child, adolescent, adult
  • The goal of carbohydrate intake – lose or gain weight

Keep in mind that the goal of monitoring your diet, including your carbohydrate intake, is one step of your overall strategy to manage blood sugar levels. In your attempts to do so, make sure you utilize the glycemic index (GI) as well as carbohydrate counting.[4]

What are Proteins?

Protein molecules, like carbohydrates contain atoms of carbon, hydrogen and oxygen. Yet, unlike carbohydrates, they also have nitrogen atoms as well as sulfur. Like carbohydrates, proteins supply energy for the body, but it’s not the body’s first choice of energy source. In fact, the brain can not use protein or fat as an energy source; it can only use glucose. Carbohydrates, proteins and fat make up the 3 major sources of energy. Insulin plays a role in all three sources.

Protein Sources

Proteins are available from both animal and vegetable food. As a result, it is found in large quantities in beans, cereals, dairy products, eggs, lentils, meat, peas and potatoes.[5] When you are looking at these sources of proteins remember that while animal products contain essential amino acids, many vegetable sources do not.

What Do Proteins Do?

Saccharides are the building blocks of a carbohydrate. In protein, this job is undertaken and fulfilled by amino acids. They number 20 and are classified according to their side chains into 7 groups. If united together by a physico-chemical peptide bond two amino acids form one dipeptide. If 2 bonds exist with 3 amino acids, the result is a tripeptide. This provides numerous circulating varieties of peptides, all playing a significant role in the metabolism.[6]

The body is able to manufacture approximately half of the 20 amino acids employed in normal metabolism in the liver by synthesizing other amino acids. Proteins from food sources arrive as essential amino acids after being broken down in the gastrointestinal tract (GI). Thus, proteins provide essential amino acids and the building supplies needed for the biosynthesis of non-essential amino acids. Amino acids are involved in a number of physical processes that include building, mending or preserving the body’s own tissues. Some are converted into glucose or triglycerides.

It should be noted that eating protein in reasonable quantities does not, usually, tend to bring about a rise in the blood sugar levels.

General Protein Requirements

You require protein to ensure your body is healthy. The requirements for an adult are 0.36 gm per pound of body weight per day. If you are undergoing metabolic stress resulting from trauma, illness or related issues, your demand for protein will climb. You will also need more protein if you become pregnant – around 70 gm. Children, particularly infants, also have different requirements. Talk to a pediatrician to ensure they are getting the right amount.


Protein and carbohydrates are both important to keeping your body fit and healthy. If you are diabetic, you may need to adjust the quantities of these two essential elements. Before you play with quantities, qualities and types, talk to an expert. A dietician can help you prepare a meal plan that will address any specific goals you have. These may include losing weight in order to keep your blood sugar level on track.


[1] Murray, R.K; Bender, DA; Botham, KM; Kennelly, PJ; Rodwell, VW; and Weil, PA (2009). Harper’s Illustrated Biochemistry 28th ed. New York: Lange McGraw Hill.

[2] Guyton, AC; and Hall, JE (2011). Textbook of Medical Physiology, 12th ed. Philadelphia: Saunders.

[3] Warshaw, HS; and Pape, J (2009). Real-Life Guide To Diabetes. Alexandria, VA: ADA.

[4] Masharani, U (2008). Diabetes DeMYSTiFieD. New York: McGraw Hill.

[5] Warshaw, op. cit.

[6] Murray, op. cit.

This article was originally published July 12, 2012 and last revision and update of it was 9/10/2015.