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Maintaining blood sugar levels is crucial for overall health and preventing a range of chronic diseases, like diabetes, cardiovascular disease, and metabolic syndrome. Keep reading to learn about how proper monitoring and management of blood sugar can help prevent these conditions, enhance patient outcomes, and improve quality of life overall.

Blood sugar regulation and related health concerns

Blood sugar regulation involves a complex interplay of hormones that maintain glucose homeostasis—specifically insulin and glucagon. Insulin facilitates glucose uptake by cells, lowering blood sugar levels, while glucagon promotes the release of glucose from the liver, raising blood sugar levels. (Röder 2016) Disruptions in this balance can lead to hyperglycemia or hypoglycemia, each with significant health implications.

Chronic hyperglycemia, a hallmark of diabetes, can cause damage to cells and organs. It increases the risk of cardiovascular diseases, kidney failure, neuropathy, and retinopathy. (Giri 2018) Conversely, hypoglycemia can cause acute symptoms like dizziness, confusion, and even loss of consciousness, posing immediate health risks. (Endocrine Society 2022)

Clinical indications for blood sugar testing

Various symptoms and risk factors may indicate the need for blood sugar testing in patients.

Assessing metabolic health

Blood sugar levels provide insight into overall metabolic function and can guide interventions to improve health outcomes. (National Institutes of Health 2024)

Evaluating hypo- or hyperglycemia symptoms

If a patient is experiencing symptoms like fatigue, excessive thirst, frequent urination, headaches, and blurred vision, this may be a sign of hyperglycemia. Consistent hunger, nervousness, shakiness, and sweating are all symptoms that may suggest hypoglycemia. Since blood sugar dysregulation can lead to these conditions if left unaddressed, laboratory screening for insulin sensitivity and blood sugar control is an effective way to confirm the diagnosis. (Endocrine Society 2022) (National Library of Medicine n.d.)

Monitoring and screening for diabetes

When working with patients to manage diabetes, blood sugar testing is a great way to assess the effectiveness of treatment strategies and make any necessary adjustments. (NIDDK 2024) It can also help screen for and diagnose diabetes in patients who are experiencing symptoms or who are at greater risk of developing it due to lifestyle factors or family medical history. (CDC 2024)

Blood sugar testing is a useful diagnostic tool for diabetes that can also be used for monitoring diabetes management effectiveness. 

Risk assessment for cardiovascular disease

Blood sugar regulation plays a significant role in heart health. Studies have found elevated blood sugar levels to be linked to cardiovascular disease risk and mortality. In particular, high blood sugar may worsen atherosclerosis and heart failure. (Poznyak 2022) Testing a patient’s metabolic function can help evaluate their risk of developing cardiovascular diseases.

Types of blood sugar tests

Understanding the various blood sugar testing options available is essential for providing comprehensive care.

Fasting blood sugar

Fasting blood sugar (FBS) tests measure blood glucose after fasting for eight hours. It’s a primary test for diagnosing diabetes and prediabetes. Normal values are typically below 100 mg per dL, with 100–125 mg per dL indicating prediabetes and 126 mg per dL or higher suggesting diabetes. (World Health Organization n.d.) While FBS is a useful diagnostic tool, it may not adequately capture insulin resistance early or postprandial blood sugar response.

Hemoglobin A1C

A hemoglobin A1C (A1C) test reflects average blood sugar levels over the previous 2–3 months by measuring the percentage of glycated hemoglobin. Unlike FBS, which measures blood glucose levels at a single point in time after an overnight fast, A1C gives a broader picture of overall glucose control, offering insight into long-term trends and making it a more reliable indicator of chronic glycemic control. An A1C below 5.7% is considered normal, 5.7–6.4% indicates prediabetes, and 6.5% or higher suggests diabetes. (Eyth 2023) (National Library of Medicine n.d.)

Fasting insulin

A fasting insulin test measures insulin levels after fasting for 8–12 hours. Often monitored to assess pancreatic function, it’s also considered a more sensitive and proactive indicator of insulin resistance than FBS and A1C. Elevated fasting insulin can indicate insulin resistance, which is a precursor to type 2 diabetes. This increase in fasting insulin can occur well before any noticeable changes in fasting blood sugar, making fasting insulin a more sensitive early indicator of insulin resistance.

By identifying insulin resistance at an early stage, clinicians can take a more proactive approach in preventing advancing metabolic syndrome. (Legro 1998) (National Library of Medicine n.d.) (Saravia 2015)

Glucose tolerance test

Glucose tolerance tests (GTTs) assess how the body handles a glucose load by measuring blood sugar levels before and after consuming a glucose solution. During this test, blood sugar levels are measured at multiple intervals after the patient consumes a specific amount of glucose. The most common version of this test is the oral glucose tolerance test (OGTT), where blood glucose is typically measured before the glucose intake (fasting) and then again at intervals, usually one hour and two hours after consumption. The results help determine how efficiently the body processes glucose, making it especially useful for diagnosing conditions like gestational diabetes and other forms of impaired glucose metabolism. (HealthLink BC n.d.)

Continuous glucose monitoring

Continuous glucose monitoring (CGM) involves using a small sensor placed under the skin that allows tracking of blood sugar levels in real-time by transmitting the information to a monitor or smartphone app. CGM provides blood sugar readings throughout the day and night, helping to identify patterns and trends in response to meals, physical activity, and circadian fluctuations.

It’s particularly useful for patients with type 1 diabetes or those with frequent hypoglycemic episodes. (NIDDK 2024) However, CGM has gained popularity among individuals interested in closely monitoring their blood sugar responses for better personalization of nutrition and exercise interventions.

Related lab test markers

Beyond primary blood sugar tests, there are several related markers that offer a more comprehensive view of a patient’s metabolic health.

Fatty liver markers

Elevated levels of the liver enzymes aspartate aminotransferase (AST) and alanine aminotransferase (ALT) may indicate non-alcoholic fatty liver disease (NAFLD), commonly associated with diabetes and obesity. (Marchesini 2008) High levels of gamma-glutamyl transferase have been found to be an effective diagnostic marker for metabolic syndrome and cardiovascular disease risk. (Naidu 2023)

Gastrointestinal function markers

Zonulin, a protein that regulates intestinal permeability, is emerging as a significant marker in the relationship between gut health and blood sugar control. Elevated zonulin levels have been strongly linked to increased intestinal permeability, often referred to as "leaky gut," which can trigger systemic inflammation, as evidenced by raised C-reactive protein (CRP) levels. Leaky gut is always associated with insulin resistance and metabolic disorders. (Hoshiko 2021)

Gut dysbiosis—microbiome imbalance in the gastrointestinal tract—can affect glucose metabolism and the production of short-chain fatty acids (SCFAs), which can also impair the gut barrier, ultimately causing decreased insulin sensitivity and inflammation. (Sadagopan 2023)

Gut microbiome balance can play an important role in glucose metabolism and metabolic health.

Inflammation and oxidative stress markers

Elevated levels of high-sensitivity C-reactive protein (hsCRP) indicate inflammation, which is a risk factor for cardiovascular disease, diabetes, and poor renal function. (Khattab 2022) High erythrocyte sedimentation rate (ESR) is another marker of inflammation, along with pro-inflammatory cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), which are elevated in chronic inflammation and metabolic disorders. (Tishkowski 2023) (Popko 2010)

8-hydroxy-2'-deoxyguanosine (8OH-dG) is an oxidative stress marker indicating prediabetes, diabetes, and damage within blood vessel walls that can increase the risk of cardiovascular disease. (Al-Aubaidy 2010) Another oxidative stress marker, oxidized low-density lipoprotein (oxLDL), has also been used as a predictor for type 2 diabetes and its associated metabolic changes. OxLDL has also been associated with obesity, inflammation, and cardiovascular disease risk. (Njajou 2009)

Lipid markers

Elevated triglyceride levels can indicate poor blood sugar control and increased cardiovascular risk. They are also linked with type 2 diabetes mellitus. (Miller 2011) High levels of total cholesterol and LDL are also associated with cardiovascular disease, and often linked with diabetes and insulin resistance. (Khil 2023)

Nutrients

Vitamin D deficiency has been associated with insulin resistance and the risk of developing type 2 diabetes. (Trimarco 2022) Similarly, magnesium deficiency has been linked to the development of metabolic disorders like obesity, diabetes, and inflammation, as magnesium plays an important role in glucose metabolism. (Pelczyńska 2022) Zinc deficiency can impair blood sugar control by reducing insulin secretion and increasing oxidative stress, which can contribute to insulin resistance and poor glucose metabolism. (MacKenzie 2022)

Due to changes in Western diet, trends have shown a growing imbalance in the ratio of omega-6 to omega-3 fatty acids, which has been associated with the development of metabolic disorders including diabetes mellitus. The disproportionate increase in omega-6 fatty acids such as arachidonic acid can lead to a pro-inflammatory state, supporting the development of insulin resistance. (Egalini 2023)

Other significant markers and hormones

Other notable markers and hormones to look for include:

• Adiponectin: Involved in glucose regulation and energy balance, and often dysregulated in metabolic diseases like obesity, insulin resistance, diabetes, and cardiovascular disease (Luo 2022)

• C-peptide: Reflects insulin production; low levels may indicate low insulin caused by type 1 diabetes or advanced type 2 diabetes (National Library of Medicine n.d.)

• Fructosamine: Indicates average blood sugar levels over a two- to three-week period, making it useful in monitoring diabetes (De Oliveira Andrade 2023)

• Uric acid: Elevated levels are associated with insulin resistance, type 2 diabetes, and metabolic syndrome (Kanbay 2016)

• 1,5-Anhydroglucitol (1,5-AG): Monitors fluctuating glucose levels after eating, with low levels suggesting hyperglycemia, which is a risk factor for coronary artery disease (Migała 2022)

Incorporating blood sugar testing into your practice

Blood sugar testing is vital for metabolic health assessment, offering critical insights into a patient's glucose regulation and overall health status. Regular monitoring and management of blood sugar levels are essential for preventing chronic diseases. By understanding the various tests available and related markers to look for, healthcare practitioners can provide comprehensive care, identify risk factors early, and personalize treatment plans to improve patient outcomes.