Diagnosis and Treatment of Growth Hormone Deficiency: A Position Statement from Korean Endocrine Society and Korean Society of Pediatric Endocrinology

Growth hormone (GH) deficiency is caused by congenital or acquired causes and occurs in childhood or adulthood. GH replacement therapy brings benefits to body composition, exercise capacity, skeletal health, cardiovascular outcomes, and quality of life. Before initiating GH replacement, GH deficiency should be confirmed through proper stimulation tests, and in cases with proven genetic causes or structural lesions, repeated GH stimulation testing is not necessary. The dosing regimen of GH replacement therapy should be individualized, with the goal of minimizing side effects and maximizing clinical improvements. The Korean Endocrine Society and the Korean Society of Pediatric Endocrinology have developed a position statement on the diagnosis and treatment of GH deficiency. This position statement is based on a systematic review of evidence and expert opinions.

Reference Ranges of Serum Insulin-Like Growth Factor-I and Insulin-Like Growth Factor Binding Protein-3: Results from a Multicenter Study in Healthy Korean Adults

Insulin-like growth factor-I (IGF-I) plays a pivotal role in the diagnosis and treatment of growth hormone (GH) excess or deficiency. The GH study group of the Korean Endocrine Society aims to establish the Korean reference ranges of serum IGF-I and insulin-like growth factor binding protein-3 (IGFBP-3) and assess the relationship between IGF-I and IGFBP-3 and clinical parameters. Fasting serum was collected from healthy Korean adults at health promotion centers of five hospitals nationwide. Serum IGF-I and IGFBP-3 were measured via an immunoradiometric assay using a DSL kit (Diagnostic Systems Laboratories). Serum samples from 354 subjects (180 male, 174 female) were analyzed based on sex at 10-year intervals from 21 to 70 years. IGF-I levels were inversely correlated with age. After adjustment of age, the IGF-I/IGFBP-3 ratio was significantly negatively associated with blood pressure and free thyroxine and positively associated with weight, hemoglobin, creatinine, alanine transferase, fasting glucose, and thyroid stimulating hormone. Therefore, age- and sex-specific reference ranges of serum IGF-I and IGFBP-3 can be efficient in evaluating GH excess or deficiency in Korean population.

Reference Ranges of Serum Insulin-Like Growth Factor-I and Insulin-Like Growth Factor Binding Protein-3: Results from a Multicenter Study in Healthy Korean Adults

Insulin-like growth factor-I (IGF-I) plays a pivotal role in the diagnosis and treatment of growth hormone (GH) excess or deficiency. The GH study group of the Korean Endocrine Society aims to establish the Korean reference ranges of serum IGF-I and insulin-like growth factor binding protein-3 (IGFBP-3) and assess the relationship between IGF-I and IGFBP-3 and clinical parameters. Fasting serum was collected from healthy Korean adults at health promotion centers of five hospitals nationwide. Serum IGF-I and IGFBP-3 were measured via an immunoradiometric assay using a DSL kit (Diagnostic Systems Laboratories). Serum samples from 354 subjects (180 male, 174 female) were analyzed based on sex at 10-year intervals from 21 to 70 years. IGF-I levels were inversely correlated with age. After adjustment of age, the IGF-I/IGFBP-3 ratio was significantly negatively associated with blood pressure and free thyroxine and positively associated with weight, hemoglobin, creatinine, alanine transferase, fasting glucose, and thyroid stimulating hormone. Therefore, age- and sex-specific reference ranges of serum IGF-I and IGFBP-3 can be efficient in evaluating GH excess or deficiency in Korean population.

Analysis of diabetes quality assessment findings and future directions for the appropriate management of diabetes in Korea

BACKGROUND/AIMS: Due to recent increases in the disease burden of diabetes mellitus, the Health Insurance Review and Assessment Service (HIRA) of Korea implemented a quality assessment of the treatment of diabetes to improve patient care. The present study was conducted to identify any changes after the implementation of the diabetes quality assessment (DQA). METHODS: The present study evaluated eight quality assessment indicators that were proposed by the HIRA in all patients with diabetes who visited a university hospital in Korea between 2009 and 2014. The indicators were statistically compared according to the characteristics of the subjects. RESULTS: There were several significant differences in the indicators among the subjects according to their demographic characteristics. Female patients had a higher continuity of treatment (COT) than that of male patients, and the insulin-treated group had a higher COT than that of the non-treated group, as well as a higher rate of undergoing the diabetes complication tests (DCTs). Patients between 40 and 80 years of age had the highest COT, while patients under 40 years of age had the lowest COT but the highest rate of taking the DCTs. Patients receiving treatment from an endocrinologist exhibited higher numbers of DCTs performed but displayed lower proportions for the prescription indicators. CONCLUSIONS: The present analysis of the DQA findings revealed that endocrinologists combine prevention and management of diabetes complications with measures for glycemic control. Thus, the effective management of diabetes likely entails systematic joint treatment regimens that involve an endocrinologist.

Medical Treatment with Somatostatin Analogues in Acromegaly: Position Statement / 대한내과학회지

Acromegaly is a chronic disorder caused by excessive growth hormone (GH) secretion. In most cases, the excess GH originates from GH-producing pituitary adenomas. Surgery is the preferred first-line treatment for patients with acromegaly, but medical management is considered when the disease persists after surgery or in cases where patients refuse surgery or are poor candidates for surgery. Somatostatin analogues are commonly used to treat acromegaly. The Korean Endocrine Society and the Korean Neuroendocrine Study Group have developed a position statement for the use of somatostatin analogues in the medical treatment of acromegaly. This position statement is based on evidence from the current literature and expert opinions. In the case of discrepancies among expert opinions, the experts voted to determine the recommended approach.

Medical Treatment with Somatostatin Analogues in Acromegaly: Position Statement / 대한내과학회지

Acromegaly is a chronic disorder caused by excessive growth hormone (GH) secretion. In most cases, the excess GH originates from GH-producing pituitary adenomas. Surgery is the preferred first-line treatment for patients with acromegaly, but medical management is considered when the disease persists after surgery or in cases where patients refuse surgery or are poor candidates for surgery. Somatostatin analogues are commonly used to treat acromegaly. The Korean Endocrine Society and the Korean Neuroendocrine Study Group have developed a position statement for the use of somatostatin analogues in the medical treatment of acromegaly. This position statement is based on evidence from the current literature and expert opinions. In the case of discrepancies among expert opinions, the experts voted to determine the recommended approach.

Medical Treatment with Somatostatin Analogues in Acromegaly: Position Statement

The Korean Endocrine Society (KES) published clinical practice guidelines for the treatment of acromegaly in 2011. Since then, the number of acromegaly cases, publications on studies addressing medical treatment of acromegaly, and demands for improvements in insurance coverage have been dramatically increasing. In 2017, the KES Committee of Health Insurance decided to publish a position statement regarding the use of somatostatin analogues in acromegaly. Accordingly, consensus opinions for the position statement were collected after intensive review of the relevant literature and discussions among experts affiliated with the KES, and the Korean Neuroendocrine Study Group. This position statement includes the characteristics, indications, dose, interval (including extended dose interval in case of lanreotide autogel), switching and preoperative use of somatostatin analogues in medical treatment of acromegaly. The recommended approach is based on the expert opinions in case of insufficient clinical evidence, and where discrepancies among the expert opinions were found, the experts voted to determine the recommended approach.

Cardio-Ankle Vascular Index as a Surrogate Marker of Early Atherosclerotic Cardiovascular Disease in Koreans with Type 2 Diabetes Mellitus

BACKGROUND: Carotid artery intima medial thickness (IMT), brachial-ankle pulse wave velocity (baPWV), and ankle-brachial index (ABI) are commonly used surrogate markers of subclinical atherosclerosis in patients with type 2 diabetes mellitus (T2DM). The cardio-ankle vascular index (CAVI) is a complement to the baPWV, which is affected by blood pressure. However, it is unclear which marker is the most sensitive predictor of atherosclerotic cardiovascular disease (ASCVD). METHODS: This was a retrospective non-interventional study that enrolled 219 patients with T2DM. The correlations among IMT, ABI, and CAVI as well as the relationship of these tests to the 10-year ASCVD risk were also analyzed. RESULTS: Among the 219 patients, 39 (17.8%) had ASCVD. In the non-ASCVD group, CAVI correlated significantly with IMT after adjusting for confounding variables, but ABI was not associated with CAVI or IMT. The analyses after dividing the non-ASCVD group into three subgroups according to the CAVI score ( < 8, ≥8 and < 9, and ≥9) demonstrated the significant increase in the mean IMT, 10-year ASCVD risk and number of metabolic syndrome risk factors, and decrease in the mean ABI in the high-CAVI group. A high CAVI was an independent risk factor in the non-ASCVD group for both a high 10-year ASCVD risk (≥7.5%; odds ratio [OR], 2.42; P < 0.001) and atherosclerosis (mean IMT ≥1 mm; OR, 1.53; P=0.007). CONCLUSION: In Korean patients with T2DM without ASCVD, CAVI was the most sensitive of several surrogate markers for the detection of subclinical atherosclerosis.

Effects of Rebamipide on Gastrointestinal Symptoms in Patients with Type 2 Diabetes Mellitus

BACKGROUND: Gastrointestinal (GI) symptoms are common in patients with type 2 diabetes mellitus (T2DM). Rebamipide is an effective gastric cytoprotective agent, but there are few data on its usefulness in T2DM. The aim of this study is to evaluate the improvement of GI symptoms after rebamipide treatment in patients with T2DM. METHODS: Patients with T2DM and atypical GI symptoms were enrolled. They took rebamipide (100 mg thrice daily) for 12 weeks and filled out the diabetes bowel symptom questionnaire (DBSQ) before and after rebamipide treatment. The DBSQ consisted of 10 questions assessing the severity of GI symptoms by a 1 to 6 scoring system. Changes in the DBSQ scores before and after rebamipide treatment were analyzed to evaluate any improvements of GI symptoms. RESULTS: A total of 107 patients were enrolled, and 84 patients completed the study. The mean age was 65.0±7.8, 26 patients were male (24.8%), the mean duration of T2DM was 14.71±9.12 years, and the mean glycosylated hemoglobin level was 6.97%±0.82%. The total DBSQ score was reduced significantly from 24.9±8.0 to 20.4±7.3 before and after rebamipide treatment (P<0.001). The DBSQ scores associated with reflux symptoms, indigestion, nausea or vomiting, abdominal bloating or distension, peptic ulcer, abdominal pain, and constipation were improved after rebamipide treatment (P<0.05). However, there were no significant changes in symptoms associated with irritable bowel syndrome, diarrhea, and anal incontinence. No severe adverse events were reported throughout the study. CONCLUSION: Rebamipide treatment for 12 weeks improved atypical GI symptoms in patients with T2DM.

Efficacy of a Once-Monthly Pill Containing Ibandronate and Cholecalciferol on the Levels of 25-Hydroxyvitamin D and Bone Markers in Postmenopausal Women with Osteoporosis

BACKGROUND: The present study evaluated the efficacy of a combination of ibandronate and cholecalciferol on the restoration of the levels of 25-hydroxyvitamin D (25[OH]D) and various bone markers in postmenopausal women with osteoporosis. METHODS: This was a randomized, double-blind, active-controlled, prospective 16-week clinical trial conducted in 20 different hospitals. A total of 201 postmenopausal women with osteoporosis were assigned randomly to one of two groups: the IBN group, which received a once-monthly pill containing 150 mg ibandronate (n=99), or the IBN+ group, which received a once-monthly pill containing 150 mg ibandronate and 24,000 IU cholecalciferol (n=102). Serum levels of 25(OH)D, parathyroid hormone (PTH), and various bone markers were assessed at baseline and at the end of a 16-week treatment period. RESULTS: After 16 weeks of treatment, the mean serum levels of 25(OH)D significantly increased from 21.0 to 25.3 ng/mL in the IBN+ group but significantly decreased from 20.6 to 17.4 ng/mL in the IBN group. Additionally, both groups exhibited significant increases in mean serum levels of PTH but significant decreases in serum levels of bone-specific alkaline phosphatase and C-telopeptide of type 1 collagen (CTX) at 16 weeks; no significant differences were observed between the groups. However, in subjects with a vitamin D deficiency, IBN+ treatment resulted in a significant decrease in serum CTX levels compared with IBN treatment. CONCLUSION: The present findings demonstrate that a once-monthly pill containing ibandronate and cholecalciferol may be useful for the amelioration of vitamin D deficiency in patients with postmenopausal osteoporosis. Moreover, this treatment combination effectively decreased serum levels of resorption markers, especially in subjects with a vitamin D deficiency, over the 16-week treatment period.

A Case of Type 2 Diabetes Mellitus with Severe Insulin Resistance and Dumping Syndrome after Bariatric Surgery

Patients with diabetes undergo bariatric surgery to improve sugar metabolism and to achieve weight loss. However, possible complications after bariatric surgery must be carefully considered. We report a case of uncontrolled blood sugar after bariatric surgery despite weight loss in a severely obese patient with diabetes. The patient underwent bariatric surgery in 2009 in order to lose weight and improve glycemic control. Six months after the surgery, the patient experienced dumping syndrome. The patient did actually lose weight; however, as the visceral fat/subcutaneous fat+visceral fat ratio increased, insulin resistance was not improved, and glycemic control was aggravated. The patient received proper medication for dumping syndrome including nutritional support and exercise education. Due to these efforts, the patient has maintained her weight loss, and her blood sugar level was controlled within the target range.

A Smartphone Application Signif icantly Improved Diabetes Self-Care Activities with High User Satisfaction

BACKGROUND: We developed for the first time a smartphone application designed for diabetes self-management in Korea and registered a patent for the relevant algorithm. We also investigated the user satisfaction with the application and the change in diabetes related self-care activities after using the application. METHODS: We conducted a questionnaire survey on volunteers with diabetes who were using the application. Ninety subjects responded to the questionnaire between June 2012 and March 2013. A modified version of the Summary of Diabetes Self-Care Activities (SDSCA) was used in this study. RESULTS: The survey results exhibited a mean subject age of 44.0 years old, and males accounted for 78.9% of the subjects. Fifty percent of the subjects had diabetes for less than 3 years. The majority of respondents experienced positive changes in their clinical course after using the application (83.1%) and were satisfied with the structure and completeness of the application (86.7%). Additionally, the respondents' answers indicated that the application was easy to use (96.7%) and recommendable to others (97.7%) and that they would continue using the application to manage their diabetes (96.7%). After using the Diabetes Notepad application, diabetes related self-care activities assessed by SDSCA displayed statistically significant improvements (P<0.05), except for the number of days of drinking. CONCLUSION: This smartphone-based application can be a useful tool leading to positive changes in diabetes related self-care activities and increase user satisfaction.

Acromegaly due to a Macroinvasive Plurihormonal Pituitary Adenoma and a Rectal Carcinoid Tumor

A macroinvasive pituitary adenoma with plurihormonality usually causes acromegaly and hyperprolactinemia, and also accompanies with neurologic symptoms such as visual disturbances. However, its concurrent presentation with a rectal carcinoid tumor is rarely observed. This study reports the history, biochemical, colonoscopic and immunohistochemical results of a 48-year-old female with acromegaly and hyperprolactinemia. Despite the large size and invasive nature of the pituitary adenoma to adjacent anatomical structures, she did not complain of any neurologic symptoms such as visual disturbance or headache. Immunohistochemical staining of the surgical specimen from the pituitary adenoma revealed that the tumor cells were positive for growth hormone (GH), prolactin (PRL), and thyroid stimulating hormone (TSH). Staining for pituitary-specific transcription factor-1 (Pit-1) was shown to be strongly positive, which could have been possibly contributing to the plurihormonality of this adenoma. Colonoscopy found a rectal polyp that was identified to be a carcinoid tumor using immunohistochemical staining. A macroinvasive pituitary adenoma with concomitant rectal carcinoid tumor was secreting GH, PRL, and TSH, which were believed to be in association with over-expression of Pit-1. This is the first case report of double primary tumors comprising a plurihormonal pituitary macroadenoma and rectal carcinoid tumor.

Clinical Guidelines for the Diagnosis and Treatment of Cushing's Disease in Korea

Cushing's disease (CD) is a rare disorder characterized by the overproduction of adrenocorticotropic hormone due to a pituitary adenoma that ultimately stimulates excessive cortisol secretion from the adrenal glands. Prior to the detection of pituitary adenomas, various clinical signs of CD such as central obesity, moon face, hirsutism, and facial plethora are usually already present. Uncontrolled hypercortisolism is associated with metabolic, cardiovascular, and psychological disorders that result in increased mortality. Hence, the early detection and treatment of CD are not only important but mandatory. Because its clinical manifestations vary from patient to patient and are common in other obesity-related conditions, the precise diagnosis of CD can be problematic. Thus, the present set of guidelines was compiled by Korean experts in this field to assist clinicians with the screening, diagnoses, and treatment of patients with CD using currently available tests and treatment modalities.

Celiac Disease in a Predisposed Subject (HLA-DQ2.5) with Coexisting Graves' Disease

Celiac disease is an intestinal autoimmune disorder, triggered by ingestion of a gluten-containing diet in genetically susceptible individuals. The genetic predisposition is related to human leukocyte antigen (HLA) class II genes, especially HLA-DQ2-positive patients. The prevalence of celiac disease has been estimated to be ~1% in Europe and the USA, but it is rarer and/or underdiagnosed in Asia. We report a case of celiac disease in a predisposed patient, with a HLA-DQ2 heterodimer, and Graves' disease that was treated successfully with a gluten-free diet. A 47-year-old woman complained of persistent chronic diarrhea and weight loss over a 9 month period. Results of all serological tests and stool exams were negative. However, the patient was found to carry the HLA DQ2 heterodimer. Symptoms improved after a gluten-free diet was initiated. The patient has been followed and has suffered no recurrence of symptoms while on the gluten-free diet. An overall diagnosis of celiac disease was made in a genetically predisposed patient (HLA-DQ2 heterodimer) with Graves' disease.

Correlation between serum 25-hydroxyvitamin D3 and the severity of atopic dermatitis in children with allergic or nonallergenic sensitization

PURPOSE: The aim of this study was to assess the relationship between serum 25-hydroxyvitamin D3 levels and the severity of atopic dermatitis (AD), markers of atopy (total IgE, total eosinophil count, and eosinophil cationic protein) in AD children according to allergen sensitization. METHODS: This cross-sectional study was carried out on 160 AD patients aged 1 to 18 years between March 2012 and August 2014. The AD patients (AD group) were subdivided into 2 categories according to the results of the allergic skin prick and Unicap tests: the allergic and nonallergic AD groups. We compared 25-hydroxyvitamin D3 levels between the AD and control groups. We also investigated relationships between serum 25-hydroxyvitamin D3 levels, the severity of AD, and markers of AD (total IgE, total eosinophil count, and eosinophil cationic protein) in the allergic and nonallergic AD groups. RESULTS: The average 25-hydroxyvitamin D3 levels were 30.6+/-11.7 and 23.7+/-10.0 ng/mL, respectively, in the control and AD groups (P<0.001). The average 25-hydroxyvitamin D3 levels were 19.7+/-8.6 and 27.5+/-9.8 ng/mL, respectively, in the allergic and nonallergic AD groups, with clinical implications (P<0.001). The 25-hydroxyvitamin D3 levels were not significantly associated with SCORing Atopic Dermatitis index in the allergic (P=0.004, r=-0.092) or nonallergic (P=0.610, r=-0.58) AD groups. The 25-hydroxyvitamin D3 levels were not significantly associated with the aforementioned markers of atopy in the AD group. CONCLUSION: These results suggest that 25-hydroxyvitamin D3 may play a role in the pathogenesis of AD.

Insufficient Experience in Thyroid Fine-Needle Aspiration Leads to Misdiagnosis of Thyroid Cancer

BACKGROUND: Fine-needle aspiration (FNA) of the thyroid is a widely accepted confirmatory test for thyroid cancer with high sensitivity and specificity. FNA is a simple procedure that is learned by many clinicians to enable accurate diagnosis of thyroid cancer. However, it is assumed that because the FNA test is a relatively simple procedure, its cytologic results are reliable regardless of the operator's experience. The aim of this study was to evaluate the differences in the diagnostic indices of FNA between operators with different levels of experience. METHODS: A total of 694 thyroid FNA specimens from 469 patients were reviewed, and were separated based on the experience of the clinicians who performed the procedure. One hundred and ninety were categorized in the experienced group, and 504 in the inexperienced group. All FNA results were then compared with histological data from surgically resected specimens, and the sample adequacy and diagnostic accuracy of the groups were compared. RESULTS: The age, gender, and nodule size and characteristics were similar in both groups. The sample adequacy rate was not significantly different between the experienced and nonexperienced groups (96.3% vs. 95.4%, P=0.682). However, the non-experienced group had a higher false-negative rate than the experienced group (6.4% vs. 17.2%, P=0.038), and the sensitivity of the FNA test also tended to be lower in the nonexperienced group (95.6% vs. 88.9%, P=0.065). CONCLUSION: These results suggest that FNA operators who have less experience may miss cases of thyroid cancer by performing the procedure incorrectly. As such, the experience of the FNA operator should be considered when diagnosing thyroid cancer. When clinicians are being trained in FNA, more effort should be made to increase the accuracy of the procedure; therefore, enhanced teaching programs and/or a more detailed feedback system are recommended.

Efficacy and Safety of Sustained-Release Recombinant Human Growth Hormone in Korean Adults with Growth Hormone Deficiency

PURPOSE: The administration of recombinant human growth hormone in adults with growth hormone deficiency has been known to improve metabolic impairment and quality of life. Patients, however, have to tolerate daily injections of growth hormone. The efficacy, safety, and compliance of weekly administered sustained-release recombinant human growth hormone (SR-rhGH, Declage(TM)) supplement in patients with growth hormone deficiency were evaluated. MATERIALS AND METHODS: This trial is 12-week prospective, single-arm, open-label trial. Men and women aged > or =20 years with diagnosed growth hormone deficiency (caused by pituitary tumor, trauma and other pituitary diseases) were eligible for this study. Each subject was given 2 mg (6 IU) of SR-rhGH once a week, subcutaneously for 12 weeks. Efficacy and safety at baseline and within 30 days after the 12th injection were assessed and compared. Score of Assessment of Growth Hormone Deficiency in Adults (AGHDA score) for quality of life and serum IGF-1 level. RESULTS: The IGF-1 level of 108.67+/-74.03 ng/mL was increased to 129.01+/-68.37 ng/mL (p=0.0111) and the AGHDA QoL score was decreased from 9.80+/-6.51 to 7.55+/-5.76 (p<0.0001) at week 12 compared with those at baseline. Adverse events included pain, swelling, erythema, and warmth sensation at the administration site, but many adverse events gradually disappeared during the investigation. CONCLUSION: Weekly administered SR-rhGH for 12 weeks effectively increased IGF-1 level and improved the quality of life in patients with GH deficiency without serious adverse events.

Change in Somatostatinergic Tone of Acromegalic Patients according to the Size of Growth Hormone-Producing Pituitary Tumors

The aim of this study was to investigate the relationship between somatostatinergic tone (SST) and the size of growth hormone (GH)-producing pituitary tumors. GH levels of 29 patients with newly diagnosed acromegaly were measured using a 75-gram oral glucose tolerance test (OGTT), an insulin tolerance test (ITT), and an octreotide suppression test (OST). Differences between GH levels during the ITT and the OGTT (DeltaGH(IO)), and between the OGTT and the OST at the same time point (DeltaGH(OS)) were compared according to the size of the tumor and the response pattern to the OST. DeltaGH(IO) of macroadenomas (n=22) was non-significantly higher than those of microadenomas while DeltaGH(OS) of macroadenomas were significantly higher than those of microadenomas. According to further analyses of macroadenomas based on the response pattern to the OST, GH levels during the ITT were significantly higher in non-responders. DeltaGH(OS) showed near-significant differences between responders and non-responders. In conclusion, as the size of the pituitary tumor increases, the effect of glucose on SST appears to be attenuated. Macroadenomas that are non-responders to the OST possess a portion of GH secretion exceeding the range of regulation by SST.

Hemoglobin A1c May Be an Inadequate Diagnostic Tool for Diabetes Mellitus in Anemic Subjects

BACKGROUND: Recently, a hemoglobin A1c (HbA1c) level of 6.5% has been determined to be a criterion for diabetes mellitus (DM), and it is a widely used marker for the diagnosis of DM. However, HbA1c may be influenced by a number of factors. Anemia is one of the most prevalent diseases with an influence on HbA1c; however, its effect on HbA1c varies based on the variable pathophysiology of anemia. The aim of this study was to determine the effect of anemia on HbA1c levels. METHODS: Anemic subjects (n=112) and age- and sex-matched controls (n=217) who were drug naive and suspected of having DM were enrolled. The subjects underwent an oral glucose tolerance test and HbA1c simultaneously. We compared mean HbA1c and its sensitivity and specificity for diagnosing DM between each subgroup. RESULTS: Clinical characteristics were found to be similar between each subgroup. Also, when glucose levels were within the normal range, the difference in mean HbA1c was not significant (P=0.580). However, when plasma glucose levels were above the diagnostic cutoff for prediabetes and DM, the mean HbA1c of the anemic subgroup was modestly higher than in the nonanemic group. The specificity of HbA1c for diagnosis of DM was significantly lower in the anemic subgroup (P<0.05). CONCLUSION: These results suggest that the diagnostic significance of HbA1c might be limited in anemic patients.