IntroductionType 2 diabetes mellitus (T2DM) is associated with alterations in bone mineral density (BMD), but association between prediabetes and BMD is unclear.MethodsWe analyzed BMD among the initially normoglycemic participants in the Pathobiology of Prediabetes in a Biracial Cohort (POP-ABC) study in relation to incident prediabetes during 5 years of follow-up.Results and DiscussionA total of 343 participants (193 Black, 150 White) underwent DEXA during Year 1 of POP-ABC and were followed quarterly for 5 years. The mean age was 44.2 ± 10.6 years; BMI was 30.2 ± 7.23 kg/m2. At baseline, the mean BMD was 1.176 ± 0.135 g/cm2 (1.230 ± 0.124 g/cm2 in men vs. 1.154 ± 0.134 g/cm2 in women, P<0.0001; 1.203 ± 0.114 g/cm2 in Black vs. 1.146 ± 0.150 g/cm2 in White participants, P=0.0003). During 5 years of follow-up, 101 participants developed prediabetes and 10 subjects developed T2DM (progressors); 232 were nonprogressors. Progressors to prediabetes had numerically higher baseline BMD and experienced lower 1-year decline in BMD (P<0.0001) compared with nonprogressors. From Kaplan-Meier analysis, the time to 50% prediabetes survival was 2.15 y among participants in the lowest quartile of baseline BMD, longer than those in higher quartiles (1.31 – 1.41 y). Values for BMD correlated inversely with age and adiponectin levels, and positively with BMI. In logistic regression analysis, BMD z score significantly predicted incident prediabetes: more negative BMD z scores were associated with decreased incident prediabetes (odds ratio 0.598 [95% confidence interval 0.407 - 0.877], P=0.0085), after controlling for age, BMI, change in BMI, ethnicity, blood glucose and adiponectin.ConclusionsAmong initially normoglycemic individuals, higher baseline BMD was associated with higher risk of incident prediabetes during 5 years of follow-up.

Objective: Sphingolipid (SPL) are associated with glucose dysregulation. Here, we examined plasma SPL profiles in relation to insulin action and secretion in Black and White adults. Methods: Baseline plasma levels of 58 SPLs (ceramides {CER}, monohexosyl-ceramides {MHC}, sphingomyelins {SM}, sphingosine {SO} and dihydro-SO-1-phosphate {DHS1P}) were assayed using LC-MS/MS. Insulin sensitivity was assessed by euglycemic clamp (ISI) and HOMA-IR; insulin secretion by IVGTT (AIR), HOMA-B and disposition index (DI, i.e, AIR × ISI). Results: We enrolled healthy offspring of parents with T2DM (75 Black, 65 White; mean age 47.7 ± 9.01 y, BMI 30.4 ± 6.12 kg/m2, FPG 92.9 ± 6.86 mg/dl and 2-hrPG 130 ± 28.8 mg/dl. Total SPLs showed no association with ISI or HOMA-IR but was significantly associated with insulin secretion (AIR, r=0.19, P=0.031; DI r=0.21, P=0.038). There were differential associations between individual SPLs and insulin secretion/sensitivity, but 5 of 58 SPLs (SM C16:0, SM C28:0, SM C28:1, SM C30:1 and SM C34:0) showed concurrent associations with both measures (r=0.16-0.37, P=0.04-<0.0001). Four SPLs were significantly associated with insulin secretion corrected for insulin sensitivity: MHC C14:0 (r=0.24, P=0.016); MHC C26:0 (r=0.23, P=0.025); SM C22:0 (r=0.26, P=0.009); DHS1P (r=0.27, P=0.006). Very long chain SMs correlated with BMI, waist circumference, body fat and lean mass (r=0.19-0.25, P=0.03-0.0004). Plasma CERs and SMs showed significant associations with 2hrPG (r=0.17-0.25, P=0.04-0.003) but not FPG. Conclusion: Circulating SPLs associate differentially with indices of insulin sensitivity, secretion, and adiposity. Of the 58 individual SPLs assayed, MHC C14:0 and C26:0, SM C22:0 and DHS1P showed the strongest association with insulin secretion corrected for insulin sensitivity. Disclosure P. Asuzu: None. N. Mandal: None. J. Y. Wan: None. F. B. Stentz: None. S. Dagogo-jack: None.

Background: To determine the role of ethnicity vs. heredity in glucoregulation, we assessed insulin secretion in healthy Black and White offspring of parents with T2DM. Methods: Participants were screened with 75-g OGTT, and normoglycemic enrollees underwent assessments, including anthropometry, insulin sensitivity and secretion. Basal insulin secretion (fasting insulin {FI} and HOMA-B) and dynamic secretion (insulinogenic index; corrected insulin response {CIR} from OGTT data; acute insulin response to i.v. glucose {AIR}, insulin-AUC during FSIGT, and disposition index {DI} were quantified. Insulin sensitivity (ISI) was measured with euglycemic clamp. Basal insulin clearance (molar ratio of fasting C-peptide to insulin) and dynamic clearance (molar ratio of plasma C-peptide to insulin levels during FSIGT) were determined. Results: We studied 145 Black and 123 White adults (N=268); 72% women; mean age 44.6±10.1 y. At baseline, fasting glucose (91.0 ± 7.26 vs.93.1 ± 6.31 mg/dl, P=0.012) and ISI (0.062 ± 0.048 vs. 0.077 ± 0.04, P=.014) were lower, and BMI (31.6 ± 7.64 vs. 28.9 ± 6.79, P=.0032) higher, in Black vs. White subjects. Basal insulin secretion was similar, but all measures of dynamic secretion were higher in Black vs. White offspring (Table 1). Conclusions: Insulin clearance is lower but dynamic insulin secretion is greater in Black versus White individuals with parental diabetes. Disclosure P. Asuzu: None. A. Patel: None. J. Y. Wan: None. S. Dagogo-jack: None.

The Ceramides and other Sphingolipids as Predictors of Incident Dysglycemia (CASPID) study tests the overall hypothesis that sphingolipids are pathophysiologic mediators of transition from normal glucose regulation (NGR) to prediabetes, type 2 diabetes (T2DM), and associated complications. The CASPID study utilizes two longitudinal cohorts – the Pathobiology of Prediabetes in a Biracial Cohort (POP-ABC)/Pathobiology and Reversibility of Prediabetes in a Biracial Cohort (PROP-ABC) and the Diabetes Prevention Program (DPP)/DPP Outcomes Study (DPPOS). Normoglycemic POP-ABC/PROP-ABC were followed for 10 years for progression to prediabetes and offered lifestyle intervention to reverse prediabetes. The DPP/DPPOS participants had prediabetes at enrollment, were randomized to placebo, lifestyle intervention, or metformin treatment, and followed for 11 years for progression to T2DM. Using a case–control design, we analyze 76 targeted plasma sphingolipids as predictors of progression from NGR to prediabetes (Aim 1), prediabetes to T2DM (Aim 2), response to interventions (Aim 3), and development of diabetes complications (Aim 4). A sample size of 600 subjects provides >80% power to detect a 20% difference in sphingolipid profiles between comparison groups (alpha = 0.01). At enrollment, POP-ABC participants had a mean age of 47.7 ± 9.00 years, body mass index (BMI) 30.4 ± 6.10 kg/m2, fasting glucose 92.9 ± 6.90 mg/dL, and 2-h glucose 130 ± 28.8 mg/dL; DPP participants had a mean age of 51.9 ± 9.44 years, BMI 33.7 ± 6.33 kg/m2, fasting glucose 106 ± 7.88 mg/dL, and 2-h glucose 164 ± 16.9 mg/dL. Among normoglycemic participants, those with parental history of T2DM had significantly higher baseline levels of total sphingomyelins, and lower levels of total ceramides and sphingosine, compared with control subjects without familial diabetes history. As the first such study in longitudinal human cohorts, CASPID will elucidate the role of sphingolipids in the pathogenesis of dysglycemia and facilitate the discovery of novel predictive and prognostic biomarkers.