Retrospective cohort study to examine the association between serum amylase and the incidence of type 2 diabetes mellitus, Toranomon Hospital Health Management Center Study 23 (TOPICS 23).

INTRODUCTION: Low serum amylase values are cross-sectionally associated with the prevalence of type 2 diabetes mellitus (T2DM) but have not been shown to be longitudinally associated with its incidence. This retrospective cohort (ie, historical cohort) study aimed to examine the association of previously lowered levels of serum amylase with incident T2DM. RESEARCH DESIGN AND METHODS: Examined were 8316 individuals who had annual health examinations for 6 years (ie, 7 times) at the Toranomon Hospital Health Management Center. The trajectory of serum amylase as the study exposure was classified into two elements: (1) serum amylase level at entry and (2) change in serum amylase, which was expressed as the annual change rate. The annual change rate was calculated by dividing the change in the amylase values according to follow-up periods. Regression analyses were performed to examine the association between low and decreased levels of serum amylase and the incidence of T2DM. RESULTS: Analyzed were 6917 individuals who had not developed T2DM within 1 year after cohort entry. T2DM thereafter occurred in 1021 patients. Cox regression indicated that the adjusted HR (95% CI) for incident T2DM for amylase ≤57 IU/L (quintile (Q) 1) was 0.97 (0.84 to 1.13) compared with amylase ≥58 IU/L (Q2-Q5). Logistic regression indicated that the adjusted OR (95% CI) for an annual change rate of amylase ≤-2.0% (Q1) vs ≥-1.9% (Q2-Q5) was 3.53 (3.00 to 4.16). The adjusted ORs were consistently significant throughout sensitivity analyses according to baseline amylase and the combination of age, body mass index, and hemoglobin A1c. CONCLUSIONS: Results showed that not low but previously decreased serum amylase was a risk factor for T2DM, suggesting the significance of periodic examinations of serum amylase values to detect individuals at high risk of T2DM.

Impact of introducing HbA1c into the diagnostic criteria on prevalence and cardiovascular risk profiles of individuals with newly diagnosed diabetes in Japan: the Toranomon Hospital Health Management Center Study 2 (TOPICS 2).

OBJECTIVE: To evaluate the impact of HbA1c for diagnosis of diabetes and investigate whether cardiovascular risks profiles differ among individuals with diabetes diagnosed by HbA1c or fasting plasma glucose (FPG). METHODS: This cross-sectional study involved 26,884 participants (30.6% women; aged 20-91 years) without known diabetes. Subjects were categorized into 4 groups according to the presence or absence of FPG ≥7.0 mmol/L and/or HbA1c ≥6.5%, which were American Diabetes Association criteria. Oral glucose tolerance test data were not available. RESULTS: Prevalence of undiagnosed diabetes was 3.6%. Of those individuals, 47.5% fulfilled both two criteria and 26.0% fulfilled only HbA1c criterion. Individuals with diabetes according to FPG ≥7.0 mmol/L alone were characterized as having poorly controlled hypertension while those with HbA1c ≥6.5% alone were characterized as older, female, and having lower blood pressure and γ-glutamyltransferase values. Persons with newly diagnosed diabetes by HbA1c had low HDL cholesterol and high LDL or non-HDL cholesterol levels. CONCLUSIONS: Introducing HbA1c into the diagnosis allowed detection of many previously undiagnosed cases of diabetes in Japanese individuals. Those diagnosed by FPG were characterized by hypertension and those diagnosed by HbA1c had unfavorable lipid profiles, reflecting an atherosclerotic trait.