Glucose Intolerance: Complete ICD-11 Coding Guide (5A40)
1. Introduction
Glucose intolerance represents an intermediate metabolic state of great clinical relevance, characterized by elevated blood glucose levels above normal values, yet insufficient to establish a diagnosis of diabetes mellitus. This metabolic disorder functions as a marker of increased cardiovascular risk and an indicator of potential progression to diabetes, making its identification and appropriate coding essential for longitudinal patient follow-up.
The clinical importance of glucose intolerance transcends simple laboratory alteration. Patients in this condition present significantly elevated risk of developing type 2 diabetes mellitus, cardiovascular diseases, and associated metabolic complications. Studies demonstrate that a considerable proportion of individuals with glucose intolerance progress to diabetes over a few years, especially in the absence of appropriate lifestyle interventions.
From a public health perspective, glucose intolerance represents a window of opportunity for effective preventive interventions. Lifestyle modifications, including dietary adjustments and increased physical activity, can reverse or significantly delay progression to diabetes. Early identification through appropriate screening allows implementation of preventive strategies that substantially reduce the burden of chronic noncommunicable diseases.
Correct coding using ICD-11 code 5A40 is critical for multiple reasons: it enables appropriate epidemiological tracking of this condition, facilitates analysis of clinical outcomes, ensures appropriate reimbursement for services provided, enables research on intervention effectiveness, and assures continuity of care through accurate medical records. Inadequate documentation can result in underreporting of this condition, compromising both individual care and public health policies.
2. Correct ICD-11 Code
The ICD-11 code for glucose intolerance is 5A40, classified within the chapter of "Endocrine, nutritional or metabolic disorders". This code belongs to the category "Other disorders of glucose regulation or pancreatic internal secretion", recognizing that glucose intolerance represents an alteration in carbohydrate metabolism that does not fit into the specific categories of diabetes mellitus.
The official ICD-11 definition describes glucose intolerance as a metabolic disorder characterized by hyperglycemia, with serum glucose levels elevated too high to be considered normal, although not high enough to meet the established diagnostic criteria for diabetes mellitus. This definition precisely captures the intermediate nature of this condition in the spectrum of dysglycemia.
The hierarchical structure of ICD-11 positions code 5A40 as a distinct category that allows clear differentiation of patients with glucose intolerance from those with established diabetes or other glycemic alterations. This distinction is fundamental because the prognostic implications, therapeutic strategies, and follow-up protocols differ substantially among these conditions.
Code 5A40 has subcategories that allow additional specifications when necessary, providing flexibility to document variations in clinical presentation. The appropriate use of this code facilitates communication among health professionals, ensures uniformity in clinical documentation, and enables comparative analyses in different care settings.
3. When to Use This Code
Scenario 1: Altered Oral Glucose Tolerance Test
Use code 5A40 when a patient presents with normal fasting blood glucose (less than 126 mg/dL) but demonstrates blood glucose between 140 and 199 mg/dL two hours after administration of 75g of anhydrous glucose during an oral glucose tolerance test. This is the classic scenario that defines glucose intolerance, where the body demonstrates inability to adequately process a glycemic load, without however characterizing diabetes. The patient may be asymptomatic or present with nonspecific symptoms such as fatigue or difficulty concentrating.
Scenario 2: Screening in High-Risk Patient
Apply code 5A40 when performing dysglycemia screening in a patient with multiple risk factors (obesity, family history of diabetes, metabolic syndrome) and results demonstrate glucose intolerance. For example, a 45-year-old woman with elevated body mass index, history of previous gestational diabetes, and sedentary lifestyle, who upon performing an oral glucose tolerance test presents a result of 165 mg/dL after two hours. This scenario represents a crucial opportunity for preventive intervention.
Scenario 3: Prediabetes with Associated Altered Fasting Blood Glucose
Use 5A40 when the patient presents with both altered fasting blood glucose (100-125 mg/dL) and glucose intolerance confirmed by oral glucose tolerance test. This combination indicates greater risk of progression to diabetes and justifies more rigorous monitoring. An example would be a 52-year-old man with fasting blood glucose of 115 mg/dL and postprandial blood glucose of 155 mg/dL on the tolerance test, without previous diagnosis of diabetes.
Scenario 4: Follow-up Post-Gestational Diabetes
Apply code 5A40 when a patient with a history of gestational diabetes undergoes reevaluation in the postpartum period and demonstrates glucose intolerance without criteria for diabetes. For example, a woman who had gestational diabetes controlled with diet, underwent an oral glucose tolerance test six weeks after delivery, and presented with fasting blood glucose of 95 mg/dL but blood glucose of 170 mg/dL after two hours. This situation requires longitudinal follow-up due to increased risk.
Scenario 5: Glycemic Alteration in the Context of Metabolic Syndrome
Use 5A40 when identifying glucose intolerance as a component of metabolic syndrome, where the patient presents with other criteria such as arterial hypertension, dyslipidemia, and central obesity. An example would be a 48-year-old patient with increased abdominal circumference, elevated triglycerides, low HDL, and oral glucose tolerance test demonstrating a result of 178 mg/dL after two hours, characterizing glucose intolerance within a broader metabolic context.
Scenario 6: Monitoring of Patient Using Diabetogenic Medications
Apply 5A40 when a patient on chronic use of medications that alter glycemic metabolism (corticosteroids, atypical antipsychotics, some immunosuppressants) develops documented glucose intolerance by appropriate tests, without however meeting criteria for iatrogenic diabetes. This scenario requires careful documentation of the temporal relationship between medication use and metabolic alteration.
4. When NOT to Use This Code
Code 5A40 should not be used when the patient meets diagnostic criteria for diabetes mellitus, regardless of type. If fasting blood glucose is equal to or greater than 126 mg/dL on two separate occasions, or if blood glucose two hours after oral glucose tolerance test is equal to or greater than 200 mg/dL, the appropriate diagnosis is diabetes mellitus, not glucose intolerance.
Avoid using 5A40 if the patient presents with established type 2 diabetes mellitus (code 119724091), even if blood glucose levels are temporarily controlled with treatment. Glucose intolerance represents a prediabetic state, not controlled diabetes. Once a diagnosis of diabetes is established, it remains as the primary diagnosis, even with good metabolic control.
Do not use this code for idiopathic type 1 diabetes mellitus (code 1651053999) or diabetes mellitus of another specified type (code 381961554). These conditions have pathophysiology, clinical presentation, and therapeutic approaches distinct from glucose intolerance, requiring specific coding.
Do not apply 5A40 when there is only transient and isolated elevation of blood glucose (code 307705857) without confirmation through oral glucose tolerance test. Isolated blood glucose elevations may occur in contexts of acute stress, infections, or other intercurrent conditions, not necessarily characterizing established glucose intolerance.
Avoid this code if the diagnosis of diabetes is evident but the type is not specified (code 1697306310). In these cases, use the code for unspecified type diabetes until further investigation allows more precise classification. Glucose intolerance is a distinct entity that should not be confused with diabetes of uncertain classification.
Finally, do not use 5A40 for other carbohydrate metabolism alterations such as glycogenoses, galactosemia, or other hereditary metabolic diseases that present with secondary blood glucose alterations. These conditions have specific codes within the ICD-11 classification and pathophysiology completely different from primary glucose intolerance.
5. Step-by-Step Coding Process
Step 1: Assess Diagnostic Criteria
The first fundamental step is to confirm the diagnosis of glucose intolerance through objective and standardized criteria. The oral glucose tolerance test remains the gold standard method for this diagnosis. The patient must fast for at least 8 hours, have baseline blood glucose collected, and after ingestion of 75g of anhydrous glucose dissolved in water, have blood glucose collected again at exactly two hours.
Specific diagnostic criteria require that fasting blood glucose be less than 126 mg/dL (excluding diabetes) and that blood glucose after two hours be between 140 and 199 mg/dL (characterizing intolerance). Blood glucose values after two hours equal to or greater than 200 mg/dL indicate diabetes, not glucose intolerance. It is essential that the test be performed under standardized conditions, with the patient in adequate nutritional status and without acute intercurrent illnesses that may alter glucose metabolism.
Complementary instruments include assessment of glycated hemoglobin (HbA1c), although this marker is not the primary diagnostic criterion for glucose intolerance. HbA1c values between 5.7% and 6.4% may suggest dysglycemia and indicate the need for oral glucose tolerance test for diagnostic confirmation. Detailed history taking investigating risk factors, family history, and associated symptoms complements the diagnostic evaluation.
Step 2: Verify Specifiers
After confirming the diagnosis, verify whether there are specifiers or additional characteristics that should be documented. Assess the severity of the metabolic alteration through specific blood glucose values, considering that results closer to 200 mg/dL indicate greater risk of progression to diabetes. Document the known duration of the condition, when applicable, especially if there are previous tests demonstrating temporal evolution.
Identify and record associated risk factors that influence prognosis, such as obesity (especially central obesity), sedentary lifestyle, family history of diabetes, history of gestational diabetes, polycystic ovary syndrome, use of diabetogenic medications, and presence of other components of metabolic syndrome. These factors do not alter the primary code but should be documented with additional codes when appropriate.
Verify whether there are comorbidities that modify the therapeutic approach or prognosis, such as established cardiovascular disease, chronic kidney disease, non-alcoholic fatty liver disease, or other endocrine conditions. The presence of these comorbidities may justify more aggressive interventions and more frequent follow-up, and should be appropriately coded in addition to code 5A40.
Step 3: Differentiate from Other Codes
Differentiation from code 5A41 (Low blood glucose without association with diabetes) is fundamental. While 5A40 is characterized by hyperglycemia insufficient for diabetes, 5A41 refers to episodes of hypoglycemia in individuals without established diabetes. The key difference lies in the direction of the blood glucose alteration: elevation versus reduction of glucose levels.
Code 5A42 (Increased glucagon secretion) differs substantially from 5A40 as it refers to a specific hormonal alteration involving glucagon hypersecretion, usually associated with pancreatic tumors producing this hormone (glucagonomas). The main difference lies in etiology: while glucose intolerance results from insulin resistance and/or relative insulin deficiency, increased glucagon secretion represents a specific endocrinopathy with distinct clinical manifestations.
Code 5A43 (Abnormal gastrin secretion) refers to Zollinger-Ellison syndrome and other conditions characterized by hypergastrinemia, with clinical manifestations predominantly gastrointestinal (recurrent peptic ulcers, diarrhea). The essential difference lies in the hormone involved and clinical manifestations: glucose intolerance relates to carbohydrate metabolism, while abnormal gastrin secretion primarily affects gastrointestinal function.
Step 4: Required Documentation
Adequate documentation must obligatorily include the results of the oral glucose tolerance test with specific values of fasting blood glucose and blood glucose after two hours. Record the date the test was performed, the conditions of patient preparation, and any circumstances that may have influenced the results.
Document the complete clinical evaluation including weight, height, body mass index, abdominal circumference, and blood pressure. Record family history of diabetes, personal history of gestational diabetes (when applicable), use of medications that may affect glucose metabolism, and presence of related symptoms.
Include results of relevant complementary tests such as glycated hemoglobin, lipid profile, renal function, and liver function, which assist in assessing overall cardiovascular risk and identifying comorbidities. Document guidance provided on lifestyle modifications, therapeutic goals established, and proposed follow-up plan.
Clearly record the ICD-11 code 5A40 in the electronic or physical medical record, accompanied by additional codes for relevant comorbidities and risk factors. This complete documentation ensures continuity of care, facilitates communication among professionals, and guarantees adequate epidemiological recording of this condition.
6. Complete Practical Example
Clinical Case
A 42-year-old female patient presents for routine medical consultation. She reports progressive weight gain over the past five years, totaling approximately 15 kg. She denies specific symptoms but mentions frequent fatigue and difficulty concentrating, which she attributes to work-related stress. Significant family history: mother with type 2 diabetes mellitus diagnosed at age 55, father with arterial hypertension and coronary artery disease. The patient has had two pregnancies, and during the second, seven years ago, she was diagnosed with gestational diabetes, controlled with diet alone. She denies tobacco use, consumes alcohol socially, and engages in irregular physical activity (sporadic walking).
On physical examination: weight 82 kg, height 1.62 m, BMI 31.2 kg/m² (obesity grade I), abdominal circumference 98 cm (increased), blood pressure 138/88 mmHg. Cardiovascular and respiratory examination without abnormalities. Absence of acanthosis nigricans.
Initial laboratory tests: fasting blood glucose 108 mg/dL, total cholesterol 215 mg/dL, LDL 135 mg/dL, HDL 42 mg/dL, triglycerides 190 mg/dL, glycated hemoglobin 5.9%. Renal and hepatic function normal.
Considering the fasting blood glucose at the upper limit of normal, history of gestational diabetes, obesity, and positive family history, an oral glucose tolerance test was requested. Result: fasting blood glucose 105 mg/dL, blood glucose after 2 hours 168 mg/dL.
Step-by-Step Coding
Criteria Analysis: The patient presents with fasting blood glucose below 126 mg/dL (105 mg/dL), excluding diabetes diagnosis by this criterion. The blood glucose after two hours on the oral glucose tolerance test was 168 mg/dL, placing it in the diagnostic range for glucose intolerance (140-199 mg/dL). The glycated hemoglobin of 5.9% corroborates the state of dysglycemia, although it is not a primary diagnostic criterion for glucose intolerance.
Code Selected: 5A40 - Glucose intolerance
Complete Justification: Code 5A40 is appropriate because the patient precisely meets the diagnostic criteria for glucose intolerance: fasting blood glucose below the threshold for diabetes (< 126 mg/dL) but post-glucose load blood glucose on the oral glucose tolerance test between 140 and 199 mg/dL. This condition represents an intermediate state of dysglycemia, not characterizing established type 2 diabetes mellitus, but indicating increased risk of progression to diabetes and cardiovascular complications.
The patient does not meet criteria for type 2 diabetes mellitus (code 119724091) as the blood glucose values do not reach diagnostic thresholds. It is not isolated elevated blood glucose (code 307705857) as there is confirmation through a standardized test. There is no evidence of type 1 diabetes or other specific forms of diabetes.
Complementary Codes:
- Obesity (appropriate code from the category of nutritional disorders)
- Mixed dyslipidemia (appropriate code)
- History of gestational diabetes (code for relevant personal history)
- Borderline arterial hypertension (if applicable)
Documented Follow-up Plan: Intensive counseling on lifestyle modifications including diet with restriction of refined carbohydrates and increased fiber, structured physical activity program (150 minutes weekly of moderate-intensity aerobic activity), weight reduction (goal of 5-10% of body weight). Reevaluation with fasting blood glucose and glycated hemoglobin in three months. New oral glucose tolerance test in 12 months or sooner if symptoms or changes in follow-up tests occur. Evaluation and management of dyslipidemia and borderline blood pressure.
7. Related Codes and Differentiation
Within the Same Category
5A41: Low blood glucose without association with diabetes
The main difference between 5A40 and 5A41 lies in the direction of the glycemic alteration. While glucose intolerance (5A40) is characterized by elevation of glycemic levels above normal without meeting criteria for diabetes, code 5A41 refers to episodes of hypoglycemia (low blood glucose) in individuals without established diabetes.
Use 5A41 when the patient presents with symptoms of hypoglycemia (tremors, diaphoresis, tachycardia, mental confusion) confirmed by capillary or serum glucose below 70 mg/dL, in contexts such as prolonged fasting, intense exercise, excessive alcohol consumption, or other causes of non-diabetic hypoglycemia. Use 5A40 when tests demonstrate hyperglycemia on the glucose tolerance test within the specific range of intolerance.
5A42: Increased glucagon secretion
Code 5A42 differs fundamentally from 5A40 in both etiology and clinical manifestations. Increased glucagon secretion generally results from pancreatic neuroendocrine tumors (glucagonomas) that produce excessive amounts of this hyperglycemic hormone.
Use 5A42 when there is evidence of glucagon hypersecretion documented by elevated serum levels of this hormone, associated with characteristic clinical manifestations such as necrolytic migratory erythema (specific skin lesion), weight loss, glossitis, anemia, and secondary hyperglycemia. Use 5A40 when glucose intolerance results from insulin resistance and/or relative insulin deficiency, without evidence of glucagon-producing tumor or other specific endocrinopathies.
5A43: Abnormal gastrin secretion
Code 5A43 refers to conditions characterized by hypergastrinemia, with Zollinger-Ellison syndrome being the most common example. This condition results from gastrin-producing tumors (gastrinomas), usually located in the pancreas or duodenum.
Use 5A43 when the clinical presentation includes recurrent or treatment-refractory peptic ulcers, secretory diarrhea, abdominal pain, and elevated serum gastrin levels, with confirmation by specific tests. Use 5A40 when the primary metabolic disorder involves carbohydrate metabolism, manifesting as glucose intolerance documented by oral glucose tolerance test, without evidence of hypergastrinemia or gastrointestinal manifestations typical of gastrinoma.
Differential Diagnoses
Glucose intolerance should be differentiated from established diabetes mellitus through specific glycemic criteria. Metabolic syndrome may include glucose intolerance as one of its components, but represents a more comprehensive diagnosis that should be coded separately when all criteria are present.
Conditions presenting with secondary hyperglycemia, such as hyperthyroidism, Cushing syndrome, acromegaly, and pheochromocytoma, should have the primary endocrinopathy as the principal diagnosis, with the glycemic alteration documented as a secondary manifestation. Stress hyperglycemia in contexts of severe acute illness does not characterize glucose intolerance and should not be coded as 5A40 until persistence of the metabolic alteration is confirmed after resolution of the acute condition.
8. Differences with ICD-10
In the ICD-10 classification, glucose intolerance was coded as R73.0, situated in the chapter of "Symptoms, signs and abnormal findings of clinical and laboratory examinations, not classified elsewhere". This location in chapter R reflected an understanding of glucose intolerance more as a laboratory finding than as an established clinical entity.
ICD-11 promotes glucose intolerance to the chapter of "Endocrine, nutritional or metabolic disorders" with the code 5A40, recognizing its nature as a specific metabolic disorder with defined prognostic and therapeutic implications. This change reflects the growing recognition of the clinical importance of glucose intolerance as a condition that requires active identification, documentation, and management.
The main practical changes include greater specificity in the definition, better integration with other carbohydrate metabolism disorders, and a more logical hierarchical structure that facilitates differentiation of related conditions. ICD-11 also offers greater flexibility for additional specifications through subcategories and extension axes.
The practical impact of these changes includes better epidemiological tracking of glucose intolerance, clearer recognition of this condition as a clinical entity that requires specific management and not merely as a laboratory finding, and facilitation of research on the effectiveness of preventive interventions. Healthcare professionals should familiarize themselves with this change to ensure adequate coding and take advantage of the prevention opportunities that early diagnosis provides.
9. Frequently Asked Questions
How is glucose intolerance diagnosed?
The diagnosis is established through the oral glucose tolerance test, considered the gold standard for this condition. The patient fasts for 8 hours, baseline blood glucose is collected, ingests 75g of glucose dissolved in water, and a new blood glucose measurement is performed exactly two hours later. The diagnosis is confirmed when fasting blood glucose is below 126 mg/dL but blood glucose after two hours is between 140 and 199 mg/dL. Glycated hemoglobin may suggest dysglycemia but does not replace the oral tolerance test for definitive diagnosis. It is important that the test be performed under standardized conditions, with the patient maintaining usual diet in the preceding days and without intercurrent acute illnesses.
Is treatment available in public health systems?
The management of glucose intolerance is based primarily on lifestyle modifications, which are accessible regardless of the health system. These interventions include nutritional guidance focused on a balanced diet with reduced refined carbohydrates and increased fiber, a structured physical activity program, and weight reduction when there is overweight or obesity. Public health systems generally offer consultations with health professionals for guidance, which may include nutritionists and physical educators. In some cases, when lifestyle modifications are insufficient and there is high risk of progression to diabetes, pharmacological intervention may be considered, whose availability varies among different health systems.
How long does treatment last?
The management of glucose intolerance has no fixed duration, being a continuous process aimed at preventing progression to diabetes and reducing cardiovascular risk. Lifestyle modifications should be maintained indefinitely, becoming a permanent part of the patient's habits. Initial medical follow-up is more frequent, generally with reevaluations every 3-6 months including laboratory tests. If there is sustained improvement with normalization of glycemic parameters, the interval between consultations can be extended, but periodic monitoring should continue given the risk of recurrence or progression. Some patients can completely reverse glucose intolerance with sustained lifestyle changes, while others may eventually progress to diabetes despite interventions.
Can this code be used in medical certificates?
Yes, code 5A40 can be used in medical certificates when glucose intolerance is relevant to the context of the certificate. For example, if the patient needs temporary exemption for follow-up medical consultations, tests, or participation in lifestyle modification programs. The code may also be relevant in occupational assessments or when the condition temporarily impacts work capacity. However, it is important to consider that glucose intolerance, being generally asymptomatic, rarely justifies prolonged work absence by itself. The documentation should be clear regarding the specific need that justifies the certificate, focusing on concrete aspects such as attendance at consultations or performance of tests.
What is the difference between glucose intolerance and prediabetes?
The terms "glucose intolerance" and "prediabetes" are frequently used interchangeably, but there are important nuances. Prediabetes is a broader term that encompasses both glucose intolerance (blood glucose of 140-199 mg/dL after two hours on the oral tolerance test) and impaired fasting glucose (fasting blood glucose between 100-125 mg/dL) and glycated hemoglobin between 5.7-6.4%. Glucose intolerance is, therefore, a specific form of prediabetes defined by the oral tolerance test. For ICD-11 coding purposes, code 5A40 refers specifically to glucose intolerance confirmed by oral tolerance test, being the most precise term for formal clinical documentation.
Does glucose intolerance always progress to diabetes?
Not necessarily. Studies demonstrate that a significant proportion of individuals with glucose intolerance progresses to diabetes over a few years, but this progression is not inevitable. Effective lifestyle interventions can substantially reduce the risk of progression, with some studies demonstrating risk reduction greater than 50%. Factors that influence progression include degree of obesity, level of physical activity, diet quality, presence of other components of metabolic syndrome, and genetic characteristics. Some individuals can completely reverse glucose intolerance, returning to normoglycemia, especially when they implement sustained and significant lifestyle changes early after diagnosis.
What follow-up tests are necessary?
Follow-up of glucose intolerance should include periodic glycemic monitoring through fasting blood glucose and glycated hemoglobin every 3-6 months initially, with the interval potentially extended to annually if there is stability or improvement. A new oral glucose tolerance test should be considered annually or sooner if there is worsening in follow-up parameters. In addition to glycemic monitoring, it is important to evaluate other cardiovascular risk factors including lipid profile, renal function, hepatic function, and blood pressure. Anthropometric evaluation with weight, body mass index, and abdominal circumference should be performed at all consultations to monitor the effectiveness of lifestyle interventions. In selected cases, additional tests may be necessary for evaluation of complications or comorbidities.
Are there medications to treat glucose intolerance?
Although the primary treatment of glucose intolerance is based on lifestyle modifications, some medications may be considered in specific situations. Metformin is the most studied medication in this context, demonstrating the ability to reduce the risk of progression to diabetes in individuals with glucose intolerance, especially those with significant obesity, younger age, or history of gestational diabetes. However, the effectiveness of lifestyle modifications generally exceeds that of pharmacological intervention, and international guidelines recommend prioritizing behavioral changes. The decision to initiate pharmacological treatment should be individualized, considering risk factors, patient preferences, and response to non-pharmacological interventions. Other medications may be necessary for management of comorbidities such as hypertension and dyslipidemia, which frequently coexist with glucose intolerance.
Conclusion: Appropriate coding of glucose intolerance using ICD-11 code 5A40 is fundamental for the recognition of this condition as an important clinical entity that requires appropriate identification, documentation, and management. The clear distinction between glucose intolerance and diabetes mellitus, as well as the differentiation of other alterations in glycemic metabolism, ensures diagnostic accuracy and enables implementation of effective preventive strategies. The correct use of this code facilitates epidemiological tracking, clinical research, and continuity of care, contributing to the reduction of the burden of chronic noncommunicable diseases through primary prevention of type 2 diabetes mellitus.
External References
This article was prepared based on reliable scientific sources:
- 🌍 WHO ICD-11 - Glucose intolerance
- 🔬 PubMed Research on Glucose intolerance
- 🌍 WHO Health Topics
- 📊 Clinical Evidence: Glucose intolerance
- 📋 Ministry of Health - Brazil
- 📊 Cochrane Systematic Reviews
References verified on 2026-02-04