HIGH PREVALENCE OF DIABETES MELLITUS INOLDER PEOPLE IN A RURAL AREA IN LAOS

To the Editor: The global prevalence of diabetes mellitus(DM) has been estimated as 2.8% in 2000 and to become4.4% in 2030, and the number of people with DM is ex-pected to approximately double between 2000 and 2030.1

However, the most striking demographic change in globalterms will be the increase in the proportion of peopleaged 65 and older.1 There is little population-based epide-miological data on DM in southeast Asia, and the preva-lence of DM in Laos remains unknown.1–5 In Laos, adeveloping Asian country, a previous study found ahigh prevalence of random blood glucose (RBG) higherthan 140 mg/dL (28.3%) and higher than 200 mg/dL(11.6%) in community-dwelling older people.6 The prev-alence of DM according to RBG (subjects withRBG�200 mg/dL or those taking blood glucose–loweringmedicine) in community-dwelling older people was muchhigher in Laos (11.6%) than in other nearby southeastAsian countries in the survey (1.6% in Vietnam, 1.7% inIndonesia, and 5.7% in Myanmar).6–9 In this study, toclarify the exact prevalence of DM and impaired glucosetolerance (IGT), 75-g oral glucose tolerance tests (OGTTs)were conducted in Laos.

In the previous study, examination of RBG, medicalhistory interviews, and physical examinations had beenconducted on 504 Laotians aged 60 and older (male:female 5 207:297, mean age 70.2) living in rural villages inthe Lahanam and Paxon zones in Songkhon District in Sa-vannakhet Province in Laos. The villages had a total pop-ulation of 12,009 people, with 744 people aged 60 andolder; and 504 older people were examined (67.7%of all eligible subjects). Of those tested, 72 had DM

(RBG�200 mg/dL), 180 had high RBG (110–199 mg/dL),and 252 had normal RBG (o110 mg/dL) (Figure 1).

In 2005, 252 people with high RBG (�110 mg/dL)were recommended for OGTT; of these, 209 (82.9%)agreed to participate. According to the criteria of the WorldHealth Organization, DM (fasting blood sugar (FBS)�126 mg/dL or 2-hour plasma glucose (PG)�200 mg/dL),IGT (FBS 110–125 mg/dL or 2-hour PG 140–199 mg/dL),and normal glucose tolerance (NGT) (FBSo110 mg/dL and2-hour PGo140 mg/dL) were defined using OGTT, whichindicated that there were 28 subjects (18.3%) with DM and39 (25.5%) with IGT among the 153 subjects with RBGbetween 110 and 199 mg/dL and 44 subjects (78.6%) withDM and six (10.7%) with IGT among the 56 subjects withRBG of 200 mg/dL or higher (Figure 1).

From the results of OGTT, the estimated prevalence ofDM or IGT was calculated for all 504 subjects (Figure 1).For this estimate, it was hypothesized that nonrespondersin each of the two groups (RBG 110–199 mg/dL or RBG�200 mg/dL) would have the same prevalence of DM orIGT according to OGTT as the responders. The estimatedprevalence of DM and IGT according to OGTT were asmuch as 17.7% and 10.7%, respectively. Because OGTTwas not given to people with normal RBG (o110 mg/dL),some people with IGT or DM who might have had highblood glucose levels only after glucose intake may havebeen overlooked.

A high prevalence of DM and IGT was shown in com-munity-dwelling older people in a rural area of Laos, a de-veloping southeast Asian country. This might reflect that therate of increase of DM is much faster in developing coun-tries than in developed ones.1,2 By 2030, it is estimated thatthe number of people aged 65 and older with DM will be 82million in developing countries and more than 48 million in

Estimated prevalence of DM and IGT for all 504 subjects

DM IGT NGT

%

89 54

17.7 10.736171.6

RBG < 110 mg n = 252

DM n = 28 18.3%

IGT n = 39 25.5%

NGT n = 86 56.2%

OGTT n = 153

Nonresponder n = 27

RBG = 110−199 mg/dL n = 180

DM n = 44 78.6%

IGT n = 6

10.7%

NGT n = 6

10.7%

OGTT n = 56

Nonresponder n = 16

RBG ≥ 200 mg/dL or on treatment n = 72

All subjects (RBG examination) N = 504

n

Figure 1. Estimated prevalence of diabetes mellitus (DM) and impaired glucose tolerance (IGT) in community-dwelling older peoplein Laos using 75-g oral glucose tolerance test (OGTT). OGTTwas performed on 209 subjects, 82.9% of all people in the district notedwith high random blood glucose (RBG) (�110 mg/dL). NGT 5 normal glucose tolerance.

LETTERS TO THE EDITOR 1791JAGS NOVEMBER 2006–VOL. 54, NO. 11

developed ones.1 Even considering such study limitations asthe small data sampling, the high prevalence of DM andIGT in community-dwelling older people in a developingcountry, Laos, is of particular note.

The high prevalence of DM in older people in a ruralarea in Laos could be associated with factors such as ethnicand genetic vulnerable factors, rapid economic develop-ment followed by nutritional transition, and other factors,such as the ‘‘fetal origins of disease’’ hypothesis, whichpostulates that early undernutrition increases the risk ofcertain chronic diseases in adulthood.10 It will be necessaryto investigate the causes behind the high prevalence of DMand IGT and their risk factors in Laos to prevent not onlyDM, but also related cardiovascular diseases, which areincreasing in Asian countries.

Kentaro SuzukiDepartment of Field MedicineGraduate School of Medicine

Kyoto UniversityKyoto, Japan

Kiyohito Okumiya, MD, PhDResearch Institute for Humanity and Nature

Kyoto, Japan

Masayuki Ishine, MDTaizo Wada, MD, PhD

Department of Field MedicineTeiji Sakagami, MD

Department of PsychiatryMatheus Roriz-Cruz, MD

Idiane Rosset, MDDepartment of Field MedicineGraduate School of Medicine,

Kyoto UniversityKyoto, Japan

Tiengkham Pongvongsa, MDStation of Malariology, Parasitology, and Entomology

Savannakhet Province, Lao PDR

Boungnong Boupha, MD, PhDNational Institute of Public Health

Vientiane, Lao PDR

Kozo Matsubayashi, MD, PhDCenter for Southeast Asian Studies

Kyoto UniversityKyoto, Japan

ACKNOWLEDGMENTS

Financial DisclosureKiyohito Okumiya received funding for Project 4–2 of

the Research Institute for Humanity and Nature from theJapanese Ministry of Education, Science and Culture. Thestudy was also supported by the overseas grant-in-aid ofthe Ministry of Health, Labor and Welfare, Japan.

Author Contributions: Kentaro Suzuki, Kiyohito Ok-umiya, Masayuki Ishine, Tiengkham Pongvongsa Boung-nong Boupha, and Kozo Matsubayashi conceived and

designed the project. All authors participated in the medicalsurvey in Laos. Kentaro Suzuki, Kiyohito Okumiya, andKozo Matsubayashi were engaged in analysis and interpre-tation of data and preparation of the manuscript.

Sponsor’s Role: None.

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vannakhet, Laos. Geriatr Gerontol Int 2005;5:159–167.

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community-dwelling elderly in Asia compared with those in Japan. V. West

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CARBOCYSTEINE THERAPY IN OLDER PEOPLEWITH CHRONIC OBSTRUCTIVEPULMONARY DISEASE

To the Editor: As revealed by Yasuda et al. in their paperrecently published in the Journal of the American GeriatricsSociety,1 the administration of the mucoactive agent, car-bocysteine (S-carboxymethyl-L-cysteine), to patients withchronic obstructive pulmonary disease (COPD) may haveadditional beneficial effects on the reduction of commoncolds and episodes of exacerbation. Although, a statisticallysignificant improvement was observed, there was, never-theless, a range of interindividual variation apparent withintheir treated patient group.

Metabolism is usually a major factor influencing theefficacy of a therapeutic agent, and that of carbocysteine isknown to be especially complex, with the pathways of de-carboxylation, N-acetylation, sulfoxidation, and ester gluco-ronidation all being involved to differing degrees.2–5 It isthis consequent spectrum of metabolites to which an indi-vidual is exposed and not simply the administered parentcompound. Several studies have indicated that the metab-olism of carbocysteine varies widely within the same indi-vidual, with few sulfoxide (sulfur oxygenated) metabolitesbeing produced after nighttime administration.4,5 Such di-urnal variation in metabolism, presumably under hormonalcontrol, is overlaid on an underlying and apparently gen-etically determined ability to produce sulfur-oxygenatedmetabolites. This later spread of ‘‘sulfoxidation capacities’’separates individuals with respect to their metabolic han-dling of the drug.4,6,7 Clearly, the effects of this later inherentvariation are phenotypically more pronounced after morn-

1792 LETTERS TO THE EDITOR NOVEMBER 2006–VOL. 54, NO. 11 JAGS