Kotaro Shimokawa

Sequence Variations of the Glucokinase Gene in Japanese Subjects With NIDDM

Mutations in the glucokinase gene have been identified recently in patients with maturity-onset diabetes of the young, a subtype of NIDDM. The proposed role of glucokinase as a glucose sensor, combined with the low insulin response to glucose found in most Japanese with NIDDM, prompted us to speculate that mutations in the glucokinase gene might be one of the major causes of NIDDM in Japanese subjects. To determine the prevalence of mutations and sequence variations in the glucokinase gene, we screened all 12 exons of the glucokinase gene, including exon/intron junctions, by polymerase chain reaction followed by single-strand conformation polymorphism in 209 Japanese NIDDM subjects. In addition to the mutation in exon 7, which substituted Arg (AGG) for Gly (GGG) at codon 261 (10), a silent mutation of Pro (CCC→CCG) in exon 4 at codon 145 and several new sequence variations in intervening sequences and the 5′-untranslated region of exon 1β (β-cell-specific exon 1) were identified. Because we identified only one subject who had a structurally abnormal glucokinase molecule, we conclude that the prevalence of structural mutations in the glucokinase gene responsible for NIDDM appears to be rare among Japanese patients. To our knowledge, this is the first thorough study describing the ethnic prevalence of mutations and sequence variations in the glucokinase gene in NIDDM.

A positive family history of hypertension might be associated with an accelerated onset of type 2 diabetes: Results from the National Center Diabetes Database (NCDD-02)

Type 2 diabetes, which is characterized by a combination of decreased insulin secretion and decreased insulin sensitivity, can be delayed or prevented by healthy lifestyle behaviors. Therefore, it is important that the population in general understands their personal risk at an early age to reduce their chances of ever developing the disease. A family history of hypertension is known to be associated with insulin resistance, but the effect of a family history of hypertension on the onset of type 2 diabetes has not well been examined. We performed a retrospective study examining patient age at the time of the diagnosis of type 2 diabetes by analyzing a dataset of 1,299 patients (1,021 men and 278 women) who had been diagnosed as having type 2 diabetes during a health checkup. The mean ± standard deviation of the patient age at the time of the diagnosis of diabetes was 49.1 ± 10.4 years for patients with a family history of hypertension and 51.8 ± 11.4 years for patients without a family history of hypertension (p < 0.001). A multivariate linear regression analysis showed a significant association between a family history of hypertension and a younger age at the time of the diagnosis of type 2 diabetes, independent of a family history of diabetes mellitus and a male sex, suggesting that a positive family history of hypertension might be associated with the accelerated onset of type 2 diabetes.

Changes in Antidiabetic Drug Prescription and Glycemic Control Trends in Elderly Patients with Type 2 Diabetes Mellitus from 2005-2013: An Analysis of the National Center Diabetes Database (NCDD-03)

Objective To analyze the changes in the pharmacotherapy and glycemic control trends in elderly patients with type 2 diabetes mellitus (T2DM) in Japan. Methods We extracted the data of 7,590 patients (5,396 men and 2,194 women; median year of birth: 1945) with T2DM registered in the National Center Diabetes Database for the years 2005 to 2013, and conducted age-stratified (<65, 65-74, and ≥75 years of age) analyses. Results The hemoglobin A1c (HbA1c) levels declined from 2005 to 2013, and for those who received antihyperglycemic drug prescription, the HbA1c levels were lower in the older age group than in the younger age group. In the ≥75 age group, dipeptidyl peptidase-4 inhibitors (DPP4i) became the most frequently prescribed drug (49.1%) in 2013, and sulfonylureas remained the second-most frequently prescribed drug (37.8%) with decreased prescribed doses. The prescription ratio of oral drugs associated with a risk of hypoglycemia was higher in patients ≥75 years of age than in those <75 years of age (40.5% and 26.4%, respectively in 2013), although it showed a downward trend. The prescription rates of insulin for patients ≥75 years of age increased during the study period. Conclusion The pharmacotherapy trends for elderly patients with T2DM changed dramatically in Japan with the launch of DPP4i in 2009. Glycemic control in a considerable portion of the ≥75 age group in Japan was maintained at the expense of potential hypoglycemia by the frequent, although cautious, use of sulfonylureas, glinides and insulin.