Variation in Diabetes Management: A National Assessment of Primary Care Providers.

BACKGROUND: Glucose control is monitored primarily through ordering HbA1c levels, which is problematic in patients with glycemic variability. Herein, we report on the management of these patients by board-certified primary care providers (PCPs) in the United States. METHODS: We measured provider practice in a representative sample of 156 PCPs. All providers cared for simulated patients with diabetes presenting with symptoms of glycemic variability. Provider responses were reviewed by trained clinicians against evidence-based care standards and accepted standard of care protocols. RESULTS: Care varied widely-overall quality of care averaged 51.3%±10.6%-with providers performing just over half the evidence-based practices necessary for their cases. More worryingly, provider identified the underlying etiology of the poor glycemic control only 36.3% of the time. HbA1c was routinely ordered in 91.3% of all cases but often (59.5%) inappropriately. Ordering other tests of glycemic control (done in 15% of cases) led to significant increases in identifying the etiology of the hyperglycemia. Correctly modifying their patient's treatment was more likely to occur if doctors first identified the underlying etiology (65.9% vs 49.0%, P<0.001). We conservatively estimated a US $65/patient/visit in unnecessary testing and US $389 annually in additional care costs when the etiology was missed, translating potentially into millions of dollars of wasteful spending. CONCLUSION: Despite established evidence that HbA1c misses short-term changes in diabetes, we found PCPs consistently ordered HbA1c, rarely using other available blood tests. However, if the factors leading to poor glycemic control were recognized, PCPs were more likely to correctly alter their patient's hypoglycemic therapy.

Use of chromosome engineering to model a segmental deletion of chromosome band 7q22 found in myeloid malignancies.

Monosomy 7 and del(7q) are associated with adverse features in myeloid malignancies. A 2.5-Mb commonly deleted segment (CDS) of chromosome band 7q22 is implicated as harboring a myeloid tumor suppressor gene (TSG); however, molecular analysis of candidate TSGs has not uncovered loss of function. To determine whether haploinsufficiency for the 7q22 CDS contributes to myeloid leukemogenesis, we performed sequential gene targeting to flank a region of orthologous synteny on mouse chromosome band 5A3 with loxP sites. We then generated Mx1-Cre, 5A3(fl) mutant mice and deleted the targeted interval in vivo. Although excision was inefficient, we confirmed somatic deletion of the 5A3 CDS in the hematopoietic stem cell compartment. Mx1-Cre, 5A3(fl) mice show normal hematologic parameters and do not spontaneously develop myeloid malignancies. The 5A3(fl) deletion does not cooperate with oncogenic Kras(G12D) expression, Nf1 inactivation, or retroviral mutagenesis to accelerate leukemia development and did not modulate responsiveness to antileukemia drugs. These studies demonstrate that it is feasible to somatically delete a large chromosomal segment implicated in tumor suppression in hematopoietic cell populations in vivo; however, our data do not support the hypothesis that the 7q22/5A3 CDS interval contains a myeloid TSG.

MLL5 contributes to hematopoietic stem cell fitness and homeostasis.

MLL5 is a novel trithorax group gene and a candidate tumor suppressor gene located within a 2.5-Mb interval of chromosome band 7q22 that frequently is deleted in human myeloid malignancy. Here we show that inactivation of the Mll5 gene in mice results in a 30% reduction in the average representation of hematopoietic stem cells and in functional impairment of long-term hematopoietic repopulation potential under competitive conditions. Bone marrow cells from Mll5-deficient mice were defective in spleen colony-forming assays, and the mutant mice showed enhanced susceptibility to 5-fluorouracil-induced myelosuppression. Heterozygous and homozygous Mll5 mutant mice did not spontaneously develop hematologic cancers, and loss of Mll5 did not alter the phenotype of a fatal myeloproliferative disorder induced by oncogenic Kras in vivo. Collectively, the data reveal an important role for Mll5 in HSC homeostasis and provide a basis for further studies to explore its role in leukemogenesis.