Genetic epidemiology of non-insulin-dependent diabetes

The Effect of an Aerobic Exercise Programme on Blood Glucose Level, Cardiovascular Parameters, Peripheral Oxygen Saturation, and Body Mass Index among Southern Nigerians with Type 2 Diabetes Mellitus, Undergoing Concurrent Sulfonylurea and Metformin Treatment

BACKGROUND

Diabetes mellitus increases the risk of cardiovascular diseases and all-cause mortality. The present study investigated the effect of an eight-week aerobics programme on fasting blood sugar (FBS), cardiovascular parameters, peripheral oxygen saturation (SpO2), and body mass index (BMI) among subjects with type-2 diabetes mellitus (T2DM).

METHODS

A pretest-posttest experimental design was employed. Fifty subjects, diagnosed with T2DM, attending the Diabetes Clinic of the University of Nigeria Teaching Hospital, Enugu, were conveniently recruited, gender and age-matched, and randomised into exercise and control groups. The intervention included an eight-week aerobic exercise at 60%-79% HRmax for 45 min-60 min, 3-days per week. The FBS, SpO2, BMI, resting heart rate (RHR), and systolic (SBP) and diastolic blood pressure (DBP) of the subjects were measured before and after the intervention. The paired and independent t-test(s) were used for the analyses within and between the groups, respectively (P ≤ 0.05).

RESULTS

The exercise group had a significantly lower SBP (15.0 mmHg, P = 0.001), DBP (7.9 mmHg, P = 0.001), RHR (4.8 bpm, P = 0.001), FBS (34.9 mg/dl, P = 0.001), and BMI (2.3, P = 0.001), while the SpO2 improved by 3.9% with P = 0.001, relative to the control group.

CONCLUSION

Aerobics is an efficacious adjunct therapy in controlling the FBS level, blood pressure, BMI, and improving SpO2 among T2DM subjects.

Variance-Component Analysis of Obesity in Type 2 Diabetes Confirms Loci on Chromosomes 1q and 11q

To study genetic loci influencing obesity in nuclear families with type 2 diabetes, we performed a genome-wide screen with 325 microsatellite markers that had an average spacing of 11 cM and a mean heterozygosity of approximately 75% covering all 22 autosomes. Genotype data were obtained from 562 individuals from 178 families from the Breda Study Cohort. These families were determined to have at least two members with type 2 diabetes. As a measure of obesity, the BMI of each diabetes patient was determined. The genotypes were analyzed using variance components (VCs) analysis implemented in GENEHUNTER 2 to determine quantitative trait loci influencing BMI. The VC analysis revealed two genomic regions showing VC logarithm of odds (LOD) scores > or =1.0 on chromosome 1 and chromosome 11. The regions of interest on both chromosomes were further investigated by fine-mapping with additional markers, resulting in a VC LOD score of 1.5 on chromosome 1q and a VC LOD of 2.4 on chromosome 11q. The locus on chromosome 1 has been implicated previously in diabetes. The locus on chromosome 11 has been implicated previously in diabetes and obesity. Our study to determine linkage for BMI confirms the presence of quantitative trait loci influencing obesity in subjects with type 2 diabetes on chromosomes 1q31-q42 and 11q14-q24.

International Diabetes Federation: a consensus on Type 2 diabetes prevention

AIMS

Early intervention and avoidance or delay of progression to Type 2 diabetes is of enormous benefit to patients in terms of increasing life expectancy and quality of life, and potentially in economic terms for society and health-care payers. To address the growing impact of Type 2 diabetes the International Diabetes Federation (IDF) Taskforce on Prevention and Epidemiology convened a consensus workshop in 2006. The primary goal of the workshop and this document was the prevention of Type 2 diabetes in both the developed and developing world. A second aim was to reduce the risk of cardiovascular disease in people who are identified as being at a higher risk of Type 2 diabetes. The IDF plan for prevention of Type 2 diabetes is based on controlling modifiable risk factors and can be divided into two target groups: People at high risk of developing Type 2 diabetes. The entire population.

CONCLUSIONS

In planning national measures for the prevention of Type 2 diabetes, both groups should be targeted simultaneously with lifestyle modification the primary goal through a stepwise approach. In addition, it is important that all activities are tailored to the specific local situation. Further information on the prevention of diabetes can be found on the IDF website: http://www.idf.org/prevention.

Genome-wide screen in obese pedigrees with type 2 diabetes mellitus from a defined Dutch population

A genome scan was performed in obese type 2 diabetes mellitus pedigrees to identify susceptibility loci involved in obesity-driven type 2 diabetes mellitus. We studied the 20% most obese diabetes pedigrees from a confined Dutch population from around the town of Breda. Previously we, and others, have already shown that a susceptibility locus influencing obesity in diabetes may reside on chromosome 18p11. We now report evidence to also suggest linkage for type 2 diabetes in these obese pedigrees on chromosome regions 11p (genome-wide P-value </= 0.061) and 12q (genome-wide P-value </= 0.029), thereby confirming previous findings from corresponding regions. The linkage found in the Breda Cohort of type 2 diabetes patients is influenced by obesity. This supports the notion that a genetic predisposition to obesity is probably intertwined with a genetic predisposition to type 2 diabetes. Further efforts should address the question of how, on a genetic level, these two factors interact.

Relationship between plasma glucose concentrations and Native Hawaiian Ancestry: The Native Hawaiian Health Research Project

OBJECTIVE

To investigate the relationship between fasting glucose and 2 h glucose with percentage of Hawaiian ancestry and ethnic admixture.

DESIGN

Cross-sectional epidemiological study of type 2 diabetes and heart disease risk factor prevalence among Native Hawaiians.

SUBJECTS

A total of 578 Native Hawaiians residing in two rural communities were examined between 1993 and 1996. Sample sizes in statistical analyses varied due to missing data and selection criteria based on ethnic ancestry.

MEASUREMENTS

Percentage of Hawaiian ancestry and non-Hawaiian ethnic admixture, assessed by self-report. Fasting and 2 h post glucose challenge plasma glucose levels. Anthropometric measures (height, weight, waist and hip circumferences). Self-report of diet and physical activity. Medical history.

RESULTS

Increased Hawaiian blood quantum was significantly associated with increased fasting glucose (P=0.0047), increased body mass index (BMI; P<0.0001), waist-to-hip ratio (WHR; P=0.0103), and age (P<0.0001), but not with leisure time physical activity and total dietary caloric intake. This association was attenuated after adjusting for BMI and WHR, but not by age-adjustment alone. However, when the effects of descent from other ethnic groups was examined in a subset of participants, full-Hawaiians had significantly higher fasting glucose concentrations (7.28 mmol/l) than part-Hawaiians after adjustments for age, gender, BMI and WHR. In contrast, part-Hawaiians of predominantly Asian ancestry had the highest 2 h glucose concentrations (7.62 mmol/l).

CONCLUSION

These results suggest that ethnic admixture may be an important, but extremely complex, factor concerning the high prevalence of type 2 diabetes observed among this population. The complexity of this relationship may have obscured the relationship between ancestry and glucose tolerance in earlier observations of this population.

Defining the genetic contribution of type 2 diabetes mellitus

Type 2 diabetes mellitus is a common multifactorial genetic syndrome, which is determined by several different genes and environmental factors. It now affects 150 million people world wide but its incidence is increasing rapidly because of secondary factors, such as obesity, hypertension, and lack of physical activity. Many studies have been carried out to determine the genetic factors involved in type 2 diabetes mellitus. In this review we look at the different strategies used and discuss the genome wide scans performed so far in more detail. New technologies, such as microarrays, and the discovery of SNPs will lead to a greater understanding of the pathogenesis of type 2 diabetes mellitus and to better diagnostics, treatment, and eventually prevention.