EDITORIAL (SEE LIAO ET AL., P. 1504) Lifestyles Matter in the Prevention of Type 2 Diabetes he incidence of type 2 diabetes is in the large-scale, the first line means for moderate change in lifestyle matters. rapidly increasing worldwide due to the prevention of type 2 diabetes. What is also of importance is the fact that T the increasing occurrence of obesity Of all the former intervention studies changes in lifestyle can reduce the level of and sedentary lifestyle. Type 2 diabetes is (8–11), programs for the prevention of cardiovascular risk factors (10). no longer confined to middle-aged and type 2 diabetes were built on the current In this issue, Liao et al. (12) report elderly people but is increasingly com- knowledge of the pathogenesis of this dis- that modification of lifestyle could influ- mon among young people and even chil- ease. To summarize, if people are over- ence BMI and fat distribution in Japanese dren (1,2). Type 2 diabetes constitutes a weight, they should lose weight; if they Americans with IGT. In their study, the major health problem in both developed are sedentary, they must increase physical intervention group had a diet particularly and developing countries, and with obe- activity. In addition, a healthy diet is also low in total fat and saturated fatty acids. sity it is becoming one of the largest chal- important, i.e., reducing the intake of to- Furthermore, the endurance exercise pro- lenges to health care systems. Therefore, tal fat (saturated fatty acids in particular) gram was offered for the first 6 months to any measures to prevent or delay the de- and increasing intake of dietary fiber by persons in the intervention group. After velopment of diabetes are urgently consuming more vegetables and fruits the first 6 months, exercise in both groups needed. and whole grain cereal products. In a was not supervised. After 2 years there There is a great deal of evidence that Swedish uncontrolled study (8), it was was a 2.5-kg decrease in body weight in both genetic and environmental factors shown that an increase in physical activity the intervention versus control group, are of importance in the pathogenesis of and moderate weight loss reduced the in- and most measurements of fat content type 2 diabetes. While the genetic factors cidence of type 2 diabetes by 50% in showed favorable changes in the inter- are still poorly understood, numerous middle-aged men with IGT. In a Chinese vention group. There were more cases studies have shown that obesity (central study (9) of IGT patients, 6-year interven- with normal glucose tolerance at least obesity in particular), physical inactivity tions with diet, physical activity, and diet once during the 24 months of follow-up (3), high-fat diet, and diet rich in satu- plus physical activity resulted in an ap- in the intervention group (67 vs. 30%). rated fatty acids increase the risk of dia- proximate 30–40% reduction in diabetes Unfortunately, any change in the main betes (4,5). Furthermore, based mainly risk in both normal weight and over- cardiovascular risk factors was not re- on epidemiological studies, low intakes of weight persons. In the Finnish Diabetes ported. The authors speculated that the dietary fiber, low-glycemic carbohy- Prevention Study, 522 subjects with IGT beneficial changes could be due to the drates, and whole grain cereals have been were randomized to either the interven- changes in visceral fat content, but the shown to increase the risk of type 2 dia- tion or control group. The intervention actual results do not firmly support this betes (5). group was able to lose weight and in- idea because it was subcutaneous fat that Type 2 diabetes is preceded by a long crease physical activity, and they also re- was reduced significantly at 24 months in period of impaired glucose tolerance duced the intake of total and saturated the intervention group. It has been sug- (IGT) or milder disturbances in glucose fats and increased fiber intake more than gested that visceral fat could be of partic- metabolism. These disturbances in glu- the control group. These lifestyle changes ular importance in the pathogenesis of cose metabolism and insulin resistance resulted in a 58% reduction of diabetes metabolic syndrome and type 2 diabetes, syndrome or metabolic syndrome, char- risk. More interestingly, none in either and there might be racial and sex differ- acterized by a clustering of risk factors, group developed diabetes if they achieved ences in this respect (13,14). However, are much more common than type 2 dia- four or five of the key targets of interven- this issue is still open for debate (15). Both betes and carry an increased risk not only tion (10). In the massive Diabetes Preven- genetic and environmental factors con- for type 2 diabetes but also for cardiovas- tion Program Trial (11) there was also a tribute to the accumulation of visceral fat, cular morbidity and mortality, even in 58% reduction in the risk of diabetes in but the exact genetic background has re- early phases of impaired glucose metabo- the intervention group, while the met- mained unresolved. There is some evi- lism (6,7). Therefore, the goals of the pre- formin-treated group showed only a 31% dence that physical activity is particularly vention of type 2 diabetes and metabolic reduction. These results from lifestyle in- effective in the prevention of visceral fat syndrome are also to prevent cardiovas- tervention trials not only emphasize the accumulation. It should be noticed, how- cular diseases and long-term diabetic importance of lifestyle in the prevention ever, that the effects of physical activity complications. It is important to notice of type 2 diabetes, but they also are not limited to visceral fat but can have that changing lifestyle is our primary tar- strengthen the crucial importance of effects on muscle and lipid metabolism get in the prevention of type 2 diabetes, overweight and physical inactivity in the (16), independent of visceral fat. Never- since it is unrealistic to believe that any pathogenesis of this disease. Further- theless, it is very important to further ex- single drug we have today could become, more, they convincingly show that even amine the role of visceral fat in the 1650 DIABETES CARE, VOLUME 25, NUMBER 9, SEPTEMBER 2002 Editorial pathogenesis of metabolic disturbances, ●●●●●●●●●●●●●●●●●●●●●●● among subjects with impaired glucose including type 2 diabetes. In this context, References tolerance. New Engl J Med 344:1343– it is also crucial to take into account the 1. Mokdad AH, Ford ES, Bowman BA, Nel- 1350, 2001 impact of fetal and early childhood nutri- son DE, Engelgau MM, Vinicor F, Marks 11. Knowler WC, Barrett-Connor E, Fowler tion (17) and the complex interaction be- JS: Diabetes trends in the U.S.: SE, Hamman S, Lachin JM, Walker EA, 1990–1998. Diabetes Care 23:1278– tween the genes and lifestyles (18). Nathan DM: Reduction in the incidence 1283, 2000 of type 2 diabetes with life style interven- As for clinical practice, health care 2. Rocchini AP: Childhood obesity and dia- tion or metformin. N Engl J Med 346:393– professionals must emphasize the key role betes epidemic. New Engl J Med 346:854– 403, 2002 of weight loss, increased physical activity, 855, 2002 12. Liao D, Asberry PJ, Shofer JB, Callahan H, and healthy diet in the prevention of met- 3. World Health Organization: Prevention of Matthys C, Boyko EJ, Leonetti D, Kahn abolic syndrome and type 2 diabetes and Diabetes Mellitus: Report of a WHO Study SE, Austin M, Newell L, Schwartz RS, inform their patients that this therapy is Group . Geneva, World Health Org., 1994 Fujimoto WY: Improvement of BMI, body targeted to the mechanisms lying behind (Tech. Rep. Ser., no. 844) composition, and body fat distribution these disorders. Physicians working in 4. Hu FB, van Dam RM, Liu S: Diet and risk with lifestyle modification in Japanese primary care should pay close attention to of type 2 diabetes: the role of types of fat Americans with impaired glucose toler- and carbohydrate. Diabetologia 44:805– the recommendations to measure not ance. Diabetes Care 25:1504–1510, 2002 817, 2001 13. Boyko EJ, Fujimoto WY, Leonetti DL, only body weight but also waist of their 5. Vessby B, Uusitupa M, Hermansen K, Ric- patients and encourage them to change Newell-Morris L: Visceral adiposity and cardi G, Rivellese AA, Tapsell L, Nalsen G, the risk of type 2 diabetes: a prospective their lifestyle as a first-line treatment mo- Berglund L, Louheranta A, Rasmussen study among Japanese Americans. Diabe- dality when appropriate. This is also ac- BM, Calveret GD, Maffeone A, Pedersen tes Care 23:465–471, 2000 cording to evidence-based medicine and E, Gustafsson IB, Storlien LH: Substitut- 14. Montague CT, O’Rahilly S: The perils of nutrition; in well-controlled clinical tri- ing dietary saturated for monounsatu- portliness: causes and consequences of als, lifestyle changes have been shown rated fat impairs insulin sensitivity in visceral adiposity. Diabetes 49:883–888, healthy men and women: the KANWU- more effective than drugs in the preven- 2000 Study. Diabetologia 44:312–319, 2001 tion of type 2 diabetes in high-risk groups 15. Frayn KN: Visceral fat and insulin resis- 6. Uusitupa MIJ: Early intervention in pa- tance—causative or correlative. Br J Nutr (10,11,19). As for future studies on the tients with non-insulin-dependent diabe- 83 (Suppl. 1):S71–S77, 2000 prevention of type 2 diabetes by drugs, tes mellitus and impaired glucose 16. Zierath JR, Krook A, Wallberg-Henriks- one may ask, “Is it still ethical to have a tolerance.