Increased OCT3 Expression in Adipose Tissue With Aging: Implications for Catecholamine and Lipid Turnover and Insulin Resistance in Women.

BACKGROUND: Catecholamine-stimulated lipolysis is reduced with aging, which may promote adiposity and insulin resistance. Organic cation transporter 3 (OCT3), which is inhibited by estradiol (E2), mediates catecholamine transport into adipocytes for degradation, thus decreasing lipolysis. In this study, we investigated the association of OCT3 mRNA levels in subcutaneous adipose tissue (SAT) with aging and markers of insulin resistance in women. METHODS: SAT biopsies were obtained from 66 women with (19) or without (47) type 2 diabetes (age 22-76 years, 20.0-40.1 kg/m2). OCT3 mRNA and protein levels were measured for group comparisons and correlation analysis. SAT was incubated with E2 and OCT3 mRNA levels were measured. Associations between OCT3 single nucleotide polymorphisms (SNPs) and diabetes-associated traits were assessed. RESULTS: OCT3 mRNA and protein levels in SAT increased with aging. SAT from postmenopausal women had higher levels of OCT3 than premenopausal women, and there was a dose-dependent reduction in OCT3 mRNA levels in SAT treated with E2. OCT3 mRNA levels were negatively associated with markers of insulin resistance, and ex vivo lipolysis. OCT3 SNPs were associated with BMI, waist to hip ratio, and circulating lipids (eg, triglycerides). CONCLUSION: OCT3 mRNA and protein levels in SAT increased with aging, and mRNA levels were negatively associated with markers of insulin resistance. E2 incubation downregulated OCT3 mRNA levels, which may explain lower OCT3 mRNA in premenopausal vs postmenopausal women. High OCT3 protein levels in adipose tissue may result in increased catecholamine degradation, and this can contribute to the reduction in lipolysis observed in women with aging.

Health care registers can be instrumental for endpoint capture in clinical diabetes trials: example of microvascular complications in Swedish patients with type 2 diabetes.

AIMS: SMARTEST is a register-based randomized clinical trial (RRCT) that compares dapagliflozin to metformin in early-stage type 2 diabetes. The primary outcome includes progression of microvascular complications based on data from the Swedish National Diabetes Register (NDR). In this sub-study, the aim was to validate microvascular complication variables in the NDR against electronic health records (EHRs). METHODS: Data were extracted from EHRs of 276 SMARTEST participants with a median observation period of 3 years in the Uppsala, Örebro and Sörmland counties and compared with NDR data. Agreement was determined for all corresponding data entries as well as for progression of microvascular complications after randomization. RESULTS: The agreement for all corresponding data entries was 98.9% (Intraclass Correlation Coefficient 0.999) for creatinine and eGFR, 95.1% for albuminuria, 91.6% for foot-at-risk and 98.2% for retinopathy status (Kappa 0.67-0.91). The agreement for progression of microvascular complications was 98.0% for CKD stage, 98.9% for albuminuria grade, 96.3% for foot-at-risk grade and 99.6% for retinopathy grade progression (Gwet's AC1 0.96-1.00). CONCLUSION: Microvascular complication variables in the NDR show good agreement with EHR data. The use of a well-established national health care registry, exemplified by the NDR, for endpoint collection in RRCTs such as SMARTEST is supported by this study.