| Part 1:Lower prevalence of newly diagnosed diabetes in smokers than in non-smokers in Chinese men screened by OGTT: a nationwide case-control studyAimsA few studies have identified no association or even a protective effect of smoking against the development of diabetes mellitus. The more detailed data of this issue in Chinese men based on nationwide samples is still lacking. We explored the associations between cigarette smoking and newly diagnosed diabetes mellitus(NDM) in Chinese men.MethodsA population-based case-control analysis was conducted. We selected 16,286 male participants without previously diagnosed diabetes into this study. Prediabetes and NDM were diagnosed according to an oral glucose tolerance test(OGTT).ResultsThere were 7,184 non-smokers(42.4%), 1,519 ex-smokers(9.0%), and 8,228 current smokers(48.6%). Age-adjusted glucose concentrations(mmol/L) were significantly lower at fasting and 120 min but higher at 30 min in current smokers than in non-smokers(5.25 vs. 5.30, 6.46 vs. 6.55, 9.06 vs. 8.86, respectively, all P < 0.01). After adjustment for demographic and behavioral variables(age, region, drinking status, physical activity, education, and family history of diabetes), multivariable logistic regression revealed that(1) heavy smokers(≥ 20 pack-years) were less likely to be centrally obese or generally overweight/obese than non-smokers(adjusted odds ratio [AOR]: 0.91 and 0.84, both P < 0.05);(2) significantly negative associations of current smoking with prediabetes and NDM(AOR: 0.91 and 0.80, both P < 0.05);(3) strata analysis revealed significantly negative associations between smoking and NDM in southern Chinese men(AOR = 0.75, P = 0.009) and normal-weight men(BMI < 25 kg/m2: AOR = 0.75, P = 0.007; waist circumference < 90 cm: AOR = 0.71, P = 0.001), but not in northern Chinese men or men with central obesity or general overweight/obesity.ConclusionsLower rate of NDM is screened by OGTT in current smokers than in non-smokers in Chinese men. The negative association is more predominant in Chinese men with lower BMI/smaller waists.Part 2:Association between cigarette smoking and hyperglycemia in Chinese women screened by OGTT: a nationwide case-control study AimsWe explored the association between smoking and hyperglycemia in women. The relevant report is still scarce.MethodsA nationwide case–control study was conducted using the China National Diabetes and Metabolic Disorders Study dataset. We selected female participants without previously diagnosed diabetes into this study. Prediabetes and NDM were screened by an oral glucose tolerance test(OGTT). Insulin sensitivity and insulin resistance were evaluated by quantitative insulin sensitivity check index(QUICKI) and Homeostasis Model Assessment-Insulin Resistance(HOMA-IR), respectively.ResultsAmong the total 24,149 female subjects, 23,234(96.2%) were non-smokers, 143(0.6%) were ex-smokers, and 772(3.2%) were current smokers. According to age-adjusted mean, compared to non-smokers, current smokers showed significantly lower fasting and 120 min glucose concentrations(mmol/L)(5.14 vs. 5.23, and 6.42 vs. 6.67, both P < 0.05), higher insulin sensitivity(QUICKI)(0.358 vs. 0.355, P = 0.026) and lower insulin resistance(lg HOMA-IR [m U·mmol/L2])(0.208 vs. 0.228, P = 0.040). The differences in insulin sensitivity and resistance disappeared after additional adjustment for BMI. Smoking was negatively associated with hyperglycemia, furthermore prediabetes alone but not NDM, independently of age, region, drinking status, physical activity, education, and family history of diabetes. The corresponding AORs(95% CIs) were 0.69(0.57–0.83), 0.64(0.52–0.80), and 0.79(0.59–1.06), respectively. Current smokers were less likely to have general overweight/obesity, elevated BP and metabolic syndrome than non-smokers(all P < 0.05).ConclusionsThe prevalence of hyperglycemia and prediabetes only screened by OGTT is lower in smokers than in non-smokers in Chinese women. |
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