Glycemic control refers to the regulation of blood glucose, or sugar, to keep it within a normal range. This process is a daily focus for individuals with diabetes, but its principles are relevant to overall wellness. Maintaining stable blood sugar levels ensures the body’s cells receive a steady supply of energy and prevents potential damage from glucose levels that are consistently too high or too low.
Defining Glycemic Control
The primary objective of glycemic control is to prevent extreme fluctuations in blood sugar, including hyperglycemia (high blood glucose) and hypoglycemia (low blood glucose). Both conditions can cause immediate symptoms and contribute to long-term health issues if they occur frequently. Achieving this balance is a dynamic process, as blood sugar levels naturally change throughout the day in response to food and activity.
Ideal glycemic control involves maintaining levels within a personalized target range, not at a single, static number. These ranges are determined by a healthcare provider based on an individual’s age, health status, and medical conditions. A common target for fasting blood glucose is between 70 and 130 mg/dL (3.9 to 7.2 mmol/L).
Methods for Measuring Glycemic Control
Hemoglobin A1c (HbA1c)
One of the most common methods for assessing long-term glycemic control is the Hemoglobin A1c (HbA1c) test. This blood test provides an average of your blood glucose levels over the preceding two to three months. It works by measuring the percentage of hemoglobin, a protein in red blood cells that carries oxygen, that has become coated with sugar (glycated). For most adults with diabetes, an A1c target is below 7.0%, while levels for people without diabetes range from 4.0% to 5.7%.
Self-Monitoring of Blood Glucose (SMBG)
For real-time feedback, individuals use self-monitoring of blood glucose (SMBG) with a glucometer. This involves pricking a finger to obtain a small blood sample, which is placed on a test strip inserted into the device. The glucometer then displays the current blood glucose concentration, allowing for immediate decisions regarding food, exercise, or medication. Common times for testing include in the morning before eating (fasting), before meals, and one to two hours after meals.
Continuous Glucose Monitoring (CGM)
A more advanced approach is continuous glucose monitoring (CGM). A CGM system uses a small sensor inserted just under the skin, which measures glucose in the interstitial fluid every few minutes, 24 hours a day. This data is sent wirelessly to a reader, smartphone, or insulin pump. CGMs provide a more complete picture of glucose fluctuations, including overnight trends and a metric called “time in range” (TIR), which is the percentage of time a person’s glucose levels are within their target zone.
Key Factors That Influence Blood Sugar
Diet
Dietary intake is a primary driver of blood glucose levels, particularly the consumption of carbohydrates. When carbohydrates are digested, they are broken down into glucose, which then enters the bloodstream. Refined carbohydrates found in sugary drinks and white bread are absorbed quickly, causing a rapid spike in blood sugar. In contrast, complex carbohydrates from whole grains, which contain fiber, are digested more slowly, leading to a more gradual rise. Protein and fats also play a role by slowing the absorption of glucose from a meal.
Physical Activity
Physical activity has a significant effect on blood sugar management. During exercise, muscles use glucose for energy, which can help lower blood glucose levels. Regular physical activity also improves the body’s insulin sensitivity, meaning the cells are better able to use available insulin to take up glucose from the blood. This improved sensitivity can last for hours after the activity is completed, contributing to more stable glycemic control.
Medication
For many individuals, prescribed medications are necessary for managing blood sugar. These can include oral agents that work by stimulating the pancreas to produce more insulin, reducing glucose produced by the liver, or improving insulin sensitivity. In other cases, injectable insulin is required to supplement or replace the body’s own production, helping to move glucose from the blood into the cells for energy.
Other Influences
Other factors can also influence blood glucose levels. Stress, whether physical or emotional, can trigger the release of hormones like cortisol, which can cause blood sugar to rise. Illness or infection can also place stress on the body and lead to elevated glucose. The quality and duration of sleep can impact hormonal balance and insulin sensitivity, with poor sleep contributing to higher blood sugar readings.
Health Implications of Poor Glycemic Control
Short-Term Effects
Poor glycemic control has immediate consequences. Hyperglycemia can cause symptoms like excessive thirst, frequent urination, fatigue, and blurred vision. Hypoglycemia can cause shakiness, sweating, confusion, and irritability, and if severe, may result in loss of consciousness or seizures. These acute events disrupt daily life and can require medical attention.
Long-Term Complications
Over time, chronically elevated blood sugar levels lead to serious and lasting health complications by inflicting damage on blood vessels throughout the body. This can result in microvascular complications, which affect small blood vessels. This type of damage is the underlying cause of diabetic retinopathy (eye damage), nephropathy (kidney disease), and neuropathy (nerve damage).
The damage from poor glycemic control also extends to the large blood vessels, leading to macrovascular complications. This damage accelerates atherosclerosis, where plaque builds up inside the arteries, narrowing them and restricting blood flow. This increases the risk of major cardiovascular events. The most prominent macrovascular complications include heart disease, heart attack, and stroke, which are leading causes of mortality in individuals with poorly managed diabetes.