Change in prevalence and 6-year incidence of diabetes and impaired fasting glucose in Korean subjects living in a rural area

Development of type 2 diabetes mellitus in people with intermediate hyperglycaemia

BACKGROUND

Intermediate hyperglycaemia (IH) is characterised by one or more measurements of elevated blood glucose concentrations, such as impaired fasting glucose (IFG), impaired glucose tolerance (IGT) and elevated glycosylated haemoglobin A1c (HbA1c). These levels are higher than normal but below the diagnostic threshold for type 2 diabetes mellitus (T2DM). The reduced threshold of 5.6 mmol/L (100 mg/dL) fasting plasma glucose (FPG) for defining IFG, introduced by the American Diabetes Association (ADA) in 2003, substantially increased the prevalence of IFG. Likewise, the lowering of the HbA1c threshold from 6.0% to 5.7% by the ADA in 2010 could potentially have significant medical, public health and socioeconomic impacts.

OBJECTIVES

To assess the overall prognosis of people with IH for developing T2DM, regression from IH to normoglycaemia and the difference in T2DM incidence in people with IH versus people with normoglycaemia.

SEARCH METHODS

We searched MEDLINE, Embase, ClincialTrials.gov and the International Clinical Trials Registry Platform (ICTRP) Search Portal up to December 2016 and updated the MEDLINE search in February 2018. We used several complementary search methods in addition to a Boolean search based on analytical text mining.

SELECTION CRITERIA

We included prospective cohort studies investigating the development of T2DM in people with IH. We used standard definitions of IH as described by the ADA or World Health Organization (WHO). We excluded intervention trials and studies on cohorts with additional comorbidities at baseline, studies with missing data on the transition from IH to T2DM, and studies where T2DM incidence was evaluated by documents or self-report only.

DATA COLLECTION AND ANALYSIS

One review author extracted study characteristics, and a second author checked the extracted data. We used a tailored version of the Quality In Prognosis Studies (QUIPS) tool for assessing risk of bias. We pooled incidence and incidence rate ratios (IRR) using a random-effects model to account for between-study heterogeneity. To meta-analyse incidence data, we used a method for pooling proportions. For hazard ratios (HR) and odds ratios (OR) of IH versus normoglycaemia, reported with 95% confidence intervals (CI), we obtained standard errors from these CIs and performed random-effects meta-analyses using the generic inverse-variance method. We used multivariable HRs and the model with the greatest number of covariates. We evaluated the certainty of the evidence with an adapted version of the GRADE framework.

MAIN RESULTS

We included 103 prospective cohort studies. The studies mainly defined IH by IFG5.6 (FPG mmol/L 5.6 to 6.9 mmol/L or 100 mg/dL to 125 mg/dL), IFG6.1 (FPG 6.1 mmol/L to 6.9 mmol/L or 110 mg/dL to 125 mg/dL), IGT (plasma glucose 7.8 mmol/L to 11.1 mmol/L or 140 mg/dL to 199 mg/dL two hours after a 75 g glucose load on the oral glucose tolerance test, combined IFG and IGT (IFG/IGT), and elevated HbA1c (HbA1c5.7: HbA1c 5.7% to 6.4% or 39 mmol/mol to 46 mmol/mol; HbA1c6.0: HbA1c 6.0% to 6.4% or 42 mmol/mol to 46 mmol/mol). The follow-up period ranged from 1 to 24 years. Ninety-three studies evaluated the overall prognosis of people with IH measured by cumulative T2DM incidence, and 52 studies evaluated glycaemic status as a prognostic factor for T2DM by comparing a cohort with IH to a cohort with normoglycaemia. Participants were of Australian, European or North American origin in 41 studies; Latin American in 7; Asian or Middle Eastern in 50; and Islanders or American Indians in 5. Six studies included children and/or adolescents.Cumulative incidence of T2DM associated with IFG5.6, IFG6.1, IGT and the combination of IFG/IGT increased with length of follow-up. Cumulative incidence was highest with IFG/IGT, followed by IGT, IFG6.1 and IFG5.6. Limited data showed a higher T2DM incidence associated with HbA1c6.0 compared to HbA1c5.7. We rated the evidence for overall prognosis as of moderate certainty because of imprecision (wide CIs in most studies). In the 47 studies reporting restitution of normoglycaemia, regression ranged from 33% to 59% within one to five years follow-up, and from 17% to 42% for 6 to 11 years of follow-up (moderate-certainty evidence).Studies evaluating the prognostic effect of IH versus normoglycaemia reported different effect measures (HRs, IRRs and ORs). Overall, the effect measures all indicated an elevated risk of T2DM at 1 to 24 years of follow-up. Taking into account the long-term follow-up of cohort studies, estimation of HRs for time-dependent events like T2DM incidence appeared most reliable. The pooled HR and the number of studies and participants for different IH definitions as compared to normoglycaemia were: IFG5.6: HR 4.32 (95% CI 2.61 to 7.12), 8 studies, 9017 participants; IFG6.1: HR 5.47 (95% CI 3.50 to 8.54), 9 studies, 2818 participants; IGT: HR 3.61 (95% CI 2.31 to 5.64), 5 studies, 4010 participants; IFG and IGT: HR 6.90 (95% CI 4.15 to 11.45), 5 studies, 1038 participants; HbA1c5.7: HR 5.55 (95% CI 2.77 to 11.12), 4 studies, 5223 participants; HbA1c6.0: HR 10.10 (95% CI 3.59 to 28.43), 6 studies, 4532 participants. In subgroup analyses, there was no clear pattern of differences between geographic regions. We downgraded the evidence for the prognostic effect of IH versus normoglycaemia to low-certainty evidence due to study limitations because many studies did not adequately adjust for confounders. Imprecision and inconsistency required further downgrading due to wide 95% CIs and wide 95% prediction intervals (sometimes ranging from negative to positive prognostic factor to outcome associations), respectively.This evidence is up to date as of 26 February 2018.

AUTHORS' CONCLUSIONS

Overall prognosis of people with IH worsened over time. T2DM cumulative incidence generally increased over the course of follow-up but varied with IH definition. Regression from IH to normoglycaemia decreased over time but was observed even after 11 years of follow-up. The risk of developing T2DM when comparing IH with normoglycaemia at baseline varied by IH definition. Taking into consideration the uncertainty of the available evidence, as well as the fluctuating stages of normoglycaemia, IH and T2DM, which may transition from one stage to another in both directions even after years of follow-up, practitioners should be careful about the potential implications of any active intervention for people 'diagnosed' with IH.

Incidence and predictors of type 2 diabetes among Koreans: A 12-year follow up of the Korean Genome and Epidemiology Study

AIM

Because the incidence of type 2 diabetes in Korea has not been clearly defined, we examined the incidence of this condition and its association with impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and other risk factors in a 12-year follow-up Korean community-based prospective cohort study.

METHODS

We recruited 7542 subjects aged 40-69years without diabetes at baseline examination from the Korean Genome and Epidemiology Study and followed these subjects for 12years biennially. Diabetes was defined according to the 2010 American Diabetes Association criteria. The incidence of type 2 diabetes and the predictors of progression to diabetes were analyzed according to baseline glucose tolerance.

RESULTS

The overall incidence of type 2 diabetes was 22.1 per 1000person-years. Subjects with combined IFG-IGT at baseline had the highest incidence of diabetes, which was more than two-fold that of individuals with isolated IFG or isolated IGT (114.4 vs. 51.3 vs. 53.1 per 1000person-years). A multivariate Cox proportional hazards model analysis showed that combined IFG-IGT, which were strong predictors of diabetes, as well as age, urban residence, family history of diabetes, smoking status, abdominal obesity, hypertension, high triglycerides and low HDL cholesterols were also independently associated with progression to diabetes.

CONCLUSIONS

The incidence of type 2 diabetes is relatively high in our Korean community-based sample. Combined IFG-IGT are strong predictors of type 2 diabetes. Measurement of 2-hour plasma glucose in addition to fasting plasma glucose is necessary for the detection of individuals at high risk for development of diabetes.

A Systematic Review on the Efficacy of Amlodipine in the Treatment of Patients With Hypertension With Concomitant Diabetes Mellitus and/or Renal Dysfunction, When Compared With Other Classes of Antihypertensive Medication

The long-term cardiovascular (CV) effects of calcium channel blockers, with special focus on amlodipine, were compared with other classes of antihypertensive medications in high-risk hypertensive patient subgroups. A systematic literature review and meta-analysis was undertaken of 38 unique randomized, active-controlled, parallel-group trials comparing amlodipine/calcium channel blockers with diuretics, β-blockers, α-blockers, angiotensin-converting enzyme inhibitors, or angiotensin II receptor blockers, with ≥6-month follow-up, and which had included assessment of blood pressure (BP) and CV events [all-cause death, CV death, myocardial infarction (MI), stroke, congestive heart failure (CHF), or major CV events (MACE: MI, CHF, stroke, and CV death)], in hypertensive patients (baseline systolic/diastolic BP ≥140/≥90 mm Hg) with either concomitant diabetes and/or renal dysfunction. In hypertensive patients with diabetes, no difference was found for amlodipine versus comparators with respect to all-cause death, CV death, MACE, and MI; a decrease in stroke risk, and an increase in CHF risk, was seen. In hypertensive patients with renal dysfunction, no difference was found for amlodipine versus comparators with respect to all-cause death, CV death, MACE, MI, and CHF; a decrease in stroke risk was seen. Amlodipine was found to be at least as efficacious as all the other classes of antihypertensive agents in reducing systolic and diastolic BP. Long-term control of BP is critical for avoiding complications of hypertension in high-risk patients, particularly CV and cerebrovascular events such as stroke. This analysis has provided evidence that amlodipine is an appealing therapeutic option in the long-term management of hypertension in both diabetic and renal dysfunction patients.

Trends in Diabetes Incidence in the Last Decade Based on Korean National Health Insurance Claims Data

BACKGROUND

Epidemiological data is useful to estimate the necessary manpower and resources used for disease control and prevention of prevalent chronic diseases. We aimed to evaluate the incidence of diabetes and identify its trends based on the claims data from the National Health Insurance Service database over the last decade.

METHODS

We extracted claims data on diabetes as the principal and first additional diagnoses of National Health Insurance from January 2003 to December 2012. We investigated the number of newly claimed subjects with diabetes codes, the number of claims and the demographic characteristics of this population.

RESULTS

Total numbers of claimed cases and populations with diabetes continuously increased from 1,377,319 in 2003 to 2,571,067 by 2012. However, the annual number of newly claimed diabetic subjects decreased in the last decade. The total number of new claim patients with diabetes codes decreased as 30.9% over 2005 to 2009. Since 2009, the incidence of new diabetes claim patients has not experienced significant change. The 9-year average incidence rate was 0.98% and 1.01% in men and women, respectively. The data showed an increasing proportion of new diabetic subjects of younger age (<60 years) combined with a sharply decreasing proportion of subjects of older age (≥60 years).

CONCLUSION

There were increasing numbers of newly claimed subjects with diabetes codes of younger age over the last 10 years. This increasing number of diabetic patients will require management throughout their life courses because Korea is rapidly becoming an aging society.

Prevalence of diabetes and impaired fasting glucose among residents in the Three Gorges Reservoir Region, China

BACKGROUND

The Three Gorges Dam in China is the world's largest hydro-electric scheme in the contemporary world. After the construction of the Dam, great changes took place on the residents' lifestyles characterized by reduced physical activity due to the loss of arable land and a series of psychological problems caused by resettlement, which might be regarded as contributing factors to the development of diabetes in Three Gorges Reservoir Region (TGRR). However, there is no study that has been conducted targeting large population samples with the aim of determining the prevalence of diabetes in TGRR. This study purposed to estimate the prevalence of diabetes and impaired fasting glucose (IFG) in the adult population ≥18 years in TGRR and to evaluate the associated risk factors.

METHODS

A total of 3721 randomly selected adults, aged ≥18 years and having lived in TGRR for at least one year, participated in questionnaire-based interview from April to May 2013 and had their physical examinations and standard glucose taken. 75 g oral glucose tolerance test (OGTT) was conducted on the subjects with fasting glucose levels being ≥ 5.6 mmol/L. Diabetes and IFG were defined according to WHO 1999 criteria.

RESULTS

The age-standardized prevalence of diabetes and IFG were 7.6% (7.9% among men and 7.4% among women) and 9.0% (9.1% among men and 8.9% among women), respectively. Among the identified cases of diabetes in this study, 54.46% (171/314) were newly diagnosed. The prevalence of diabetes cases rose with age (4.0%, 4.5%, 8.1%, 11.2%, 12.4% and 12.9% among persons who were 18 to 29, 30 to 39, 40 to 49, 50 to 59, 60 to 69 and ≥ 70 years of age, respectively). The results of multivariate logistic-regression analyses showed that the diabetes was significantly linked to age, family history of diabetes, central obesity, educational level and hypertension for both men and women. In addition, smoking was significantly associated with diabetes in men.

CONCLUSIONS

Diabetes has become a major public health problem in the TGRR with a large number of the cases undiagnosed. These results suggest that regular population-based diabetes screening should be conducted to identify early-stage diabetes and integrated strategies aimed at the prevention and treatment of diabetes initiated.

Trend analysis of diabetic prevalence and incidence in a rural area of South Korea between 2003-2008

Aims/Introduction:  This study determined the change in prevalence of diabetes and prediabetes over a period of 5 years in South Korea. The incidence of diabetes and prediabetes and risk factors associated with the development of diabetes were also investigated.

Materials and Methods:  The Dalseong population‐based cohort survey recruited 1806 subjects who were over 20‐years‐old in 2003. Five years later, 1287 of the original subjects were re‐evaluated and 187 new subjects were added to the study. All participants completed a questionnaire, were given a physical examination, and provided blood samples for analysis including 2 h oral glucose tolerances.

Results:  Age‐adjusted prevalence of diabetes rose from 6.7% in 2003 to 9.1% in 2008. The prevalence of prediabetes also increased from 18.5% in 2003 to 28.4% in 2008. The incidence rates of diabetes and prediabetes were 18.3 per 1000 person‐years and 55.4 per 1000 person‐years, respectively. The development of diabetes was associated with impaired fasting glucose (IFG) (odds ratio [OR] 5.661), impaired glucose tolerance (IGT) (OR: 6.013), age (OR 1.013), and waist‐to‐hip ratio (OR 1.513). After excluding the IFG and IGT, systolic blood pressure (OR 1.023), high‐sensitivity C‐reactive protein (hsCRP; OR 1.097), triglyceride (OR 1.002) and waist‐to‐hip ratio (OR 1.696) were statistically significant risk factors in a multivariate logistic regression analysis.

Conclusions:  A significant rise in the prevalence of diabetes and prediabetes was observed between 2003 and 2008. In addition, this study newly demonstrated that waist‐to‐hip ratio and hsCRP were associated with the development of diabetes after adjusting for several confounding factors. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00045.x, 2010)

Trends in prevalence of diabetes in Asian countries

Diabetes is a major lifestyle disorder, the prevalence of which is increasing globally. Asian countries contribute to more than 60% of the world’s diabetic population as the prevalence of diabetes is increasing in these countries. Socio-economic growth and industrialization are rapidly occurring in many of these countries. The urban-rural divide in prevalence is narrowing as urbanization is spreading widely, adversely affecting the lifestyle of populations. Asians have a strong ethnic and genetic predisposition for diabetes and have lower thresholds for the environmental risk factors. As a result, they develop diabetes at a younger age and at a lower body mass index and waist circumference when compared with the Western population. The adverse effect of physical inactivity and fatty food are manifested as the increasing rate of overweightness and obesity, even among children. The health care budgets for the disease management are meager and the health care outcome is far from the optimum. As a result, complications of diabetes are common and the economic burden is very high, especially among the poor strata of the society. National endeavors are urgently needed for early diagnosis, effective management and for primary prevention of diabetes. This editorial aims to highlight the rising trend in prevalence of diabetes in Asia, its causative factors and the urgent need to implement national strategies for primary prevention of type 2 diabetes.

The epidemiology of diabetes in Korea

Diabetes is an increasing global health problem worldwide. Diabetes and its complications have become a major cause of morbidity and mortality in Korea. The prevalence of diabetes in Korea has increased six- to seven-fold from 1.5% to 9.9% in the past 40 years. The prevalence of impaired fasting glucose also increased to about 20% in 2009. The International Diabetes Federation has estimated that the prevalence of diabetes will rise to 11.4% in 2030. Possible risk factors for diabetes in Korea are age, male gender, obesity, prediabetes, gestational diabetes, smoking, decreased physical activity, and short sleep duration. With increasing obesity, especially in childhood, and improved longevity, the prevalence of diabetes is expected to dramatically increase more than previously estimated. Therefore, public efforts to introduce healthy lifestyle changes and diabetic prevention programs are necessary to reduce the global epidemic of diabetes.

Type 2 diabetes in urban and rural districts in Korea: factors associated with prevalence difference

The purpose of this study was to examine the urban-rural differences in the prevalence and associated factors with type 2 diabetes mellitus (T2DM) in Korean adults. A total of 1,060 adults >30 yr of age from urban (189 males and 331 females) and rural districts (219 males and 321 females) were recruited. Anthropometric measures, blood pressure, lipid profiles, and fasting and 2-hr after 75-g oral glucose load blood glucose were obtained. The crude- and age-standardized prevalence of T2DM was 15.4% and 14.5%, and 11.7% and 8.6% in urban and rural districts, respectively. Diabetic subjects were older and obese, and had a higher triglyceride level, and systolic blood pressure compared to non-diabetes in both population. Multivariate regression analysis revealed that older age, high triglyceride levels, central obesity, and hypertension were significantly associated with T2DM in both areas. Low monthly incomes were significantly associated with T2DM in urban population, while a family history of T2DM was significantly associated with T2DM in rural area. T2DM is more prevalent in urban than in rural population, and low economic status or genetic factor is differently associated with T2DM in both population, respectively.

Alcohol consumption and higher incidence of impaired fasting glucose or type 2 diabetes in obese Korean men

It is inconclusive whether moderate alcohol consumption reduces the diabetes risk. We observed the development of impaired fasting glucose or type 2 diabetes according to the amount of alcohol intake and body mass index. The annual health evaluation data of 2,500 male workers from 2002 to 2006 were reviewed retrospectively deleting personal identification code. The information contained sex, age, medical history, smoking status, alcohol consumption, participating regular exercise, anthropometric, and biochemistry measurement. Impaired fasting glucose or diabetes was determined when fasting plasma glucose was > or =100mg/dL. Thousand seven hundred seven subjects were eligible after excluding medical history of diabetes or fasting glucose > or =100mg/dL at baseline. The relative risks of its development in group of taking 1-14, 15-29, and > or =30.0g ethanol were 0.842 (95% confidence interval [CI], 0.603-1.176), 1.068 (95% CI, 0.736-1.551), and 1.019 (95% CI, 0.662-1.568) within normal weight group, 1.164 (95% CI, 0.795-1.705), 1.421 (95% CI, 0.947-2.133), and 1.604 (95% CI, 1.031-2.495) within overweight group, and 1.498 (95% CI, 1.042-2.153), 1.634 (95% CI, 1.091-2.447), and 1.563 (95% CI, 1.019-2.396) within obese group each after adjusting age, family history of diabetes, smoking, exercise, serum fasting glucose, aspartate aminotransferase, and gamma-glutamyltransferase with nondrinkers as a reference group. Not only high alcohol consumption but also moderate drinking was related with higher incidence of impaired fasting glucose or diabetes in obese Korean men.

Heritabilities of the metabolic syndrome phenotypes and related factors in Korean twins

CONTEXT

The genetic studies of metabolic syndrome (MetS), individual components, or latent factors of MetS phenotypes, in Asian populations are limited.

OBJECTIVE

This study aimed to estimate heritability of MetS and its components, and to identify latent factors clustering individual components among Korean twins and their families.

DESIGN

Data were derived from the Healthy Twin Study, an ongoing cohort study, from April 2005 to December 2008.

PARTICIPANTS

A total of 1942 Korean adult same-sex twins and their families (728 men, 1214 women; 795 monozygotic and 229 dizygotic twin individuals with 918 nontwin family members).

MAIN OUTCOME MEASURES

MetS phenotypes measured were waist circumference (WC), mean blood pressure (MBP), glucose, high-density lipoprotein cholesterol (HDL), and triglycerides (TG) as continuous and discrete traits. MetS was defined using Adult Treatment Panel III and International Diabetes Federation criteria. Heritability, bivariate analyses, interclass correlation, concordances, and factor analyses were conducted.

RESULTS

Significant differences in interclass correlation for WC, MBP, HDL, and glucose and in concordance rate for high WC and low HDL among monozygotic and dizygotic twins were found. MetS had heritabilities of 51-60% (P < 0.001), and phenotypes showed adjusted heritabilities ranging from 46% (for TG) to 77% (for low HDL). Factor analysis indicated two latent factors (factor 1, TG/WC/HDL; factor 2, WC/MBP/glucose) with significant heritabilities of 60-63%. Bivariate analyses exhibited different genetic and environmental interrelationships between phenotype pairs, although WC and TG showed significant genetic correlations with all other phenotypes.

CONCLUSIONS

Significant genetic contributions for MetS, its related phenotypes, and latent factors comprising MetS are confirmed.

Ethnic difference in inter-East Asian subjects with normal glucose tolerance and impaired glucose regulation: a systematic review and meta-analysis focusing on fasting serum insulin

AIMS

To investigate ethnic difference by focusing on fasting serum insulin (FSI) in inter-East Asian subjects with normal glucose tolerance (NGT) and impaired glucose regulation (IGR).

METHODS

Data sources included MEDLINE and EMBASE between 2001 and 2007. We conducted a search for articles containing mean or geometric mean values of FSI in East Asian subjects with NGT, IGR, or type 2 diabetes (T2DM). The Monte Carlo method was used for simulation of the mean and standard deviation of individual measures in each ethnic group; calculation of the median ratio and 95% confidence interval of individual measures between ethnic groups.

RESULTS

Twenty-two articles fully met our pre-determined criteria and were included in the meta-analysis. Results of the meta-analysis revealed that FSI level is significantly lower in Japanese subjects with NGT, IGR, or T2DM than in Korean and Chinese subjects.

CONCLUSIONS

Ethnic difference in FSI level between East Asians was observed in not only T2DM patients but also subjects with NGT or IGR. The lower FSI level in Japanese subjects was accompanied by lower triglyceride level. These results suggest that ethnic difference in dietary habit was one of the most influential factors for the ethnic difference in FSI.

The effect of lowering the threshold for diagnosis of impaired fasting glucose

PURPOSE

The aim of this study was to evaluate the effect of lowering the fasting plasma glucose (FPG) criteria for impaired fasting glucose (IFG) on the prevalence of IFG and the risk for the development of diabetes associated with IFG in Koreans.

MATERIALS AND METHODS

A total of 7,211 subjects who had normal glucose tolerance (NGT) or IFG were recruited. Subjects were evaluated at baseline and after two years follow up. Clinical data including total cholesterol, FPG and blood pressure were examined.

RESULTS

Lowering the criteria for IFG from 6.1 mmol/L (110 mg/dL) to 5.6 mmol/L (100 mg/dL) increased the prevalence of IFG from 6.6% (494 subjects) to 24.4% (1829 subjects). After the 2 years follow up period, 91 subjects (1.3%) developed diabetes. Twenty one (0.3%) subjects developed diabetes among 5,382 NGT subjects and 70 (3.8%) subjects developed diabetes among 1,829 IFG (5.6-7.0 mmol/L) subjects. Lowering the IFG threshold from 6.1 mmol/L to 5.6 mmol/L resulted in a 18.4% decrease in specificity and 23.9% increase in sensitivity for predicting diabetes. The baseline FPG for predicting the development of diabetes after 2 years at a point on the receiver operating characteristic curve that was closest to the ideal 100% sensitivity and 100% specificity was 5.7 mmol/L (103 mg/dL).

CONCLUSION

Lowering the FPG criterion of IFG should have benefits in predicting new onset type 2 diabetes mellitus in Koreans. The economic and health benefits of applying the new IFG criteria should be evaluated in future studies.