A systems view of type 2 diabetes-associated metabolic perturbations in saliva, blood and urine at different timescales of glycaemic control

AIMS/HYPOTHESIS

Metabolomics has opened new avenues for studying metabolic alterations in type 2 diabetes. While many urine and blood metabolites have been associated individually with diabetes, a complete systems view analysis of metabolic dysregulations across multiple biofluids and over varying timescales of glycaemic control is still lacking.

METHODS

Here we report a broad metabolomics study in a clinical setting, covering 2,178 metabolite measures in saliva, blood plasma and urine from 188 individuals with diabetes and 181 controls of Arab and Asian descent. Using multivariate linear regression we identified metabolites associated with diabetes and markers of acute, short-term and long-term glycaemic control.

RESULTS

Ninety-four metabolite associations with diabetes were identified at a Bonferroni level of significance (p < 2.3 × 10(-5)), 16 of which have never been reported. Sixty-five of these diabetes-associated metabolites were associated with at least one marker of glycaemic control in the diabetes group. Using Gaussian graphical modelling, we constructed a metabolic network that links diabetes-associated metabolites from three biofluids across three different timescales of glycaemic control.

CONCLUSIONS/INTERPRETATION

Our study reveals a complex network of biochemical dysregulation involving metabolites from different pathways of diabetes pathology, and provides a reference framework for future diabetes studies with metabolic endpoints.

1,5-Anhydroglucitol in saliva is a noninvasive marker of short-term glycemic control

CONTEXT

In most ethnicities at least a quarter of all cases with diabetes is assumed to be undiagnosed. Screening for diabetes using saliva has been suggested as an effective approach to identify affected individuals.

OBJECTIVE

The objective of the study was to identify a noninvasive metabolic marker of type 2 diabetes in saliva.

DESIGN AND SETTING

In a case-control study of type 2 diabetes, we used a clinical metabolomics discovery study to screen for diabetes-relevant metabolic readouts in saliva, using blood and urine as a reference. With a combination of three metabolomics platforms based on nontargeted mass spectrometry, we examined 2178 metabolites in saliva, blood plasma, and urine samples from 188 subjects with type 2 diabetes and 181 controls of Arab and Asian ethnicities.

RESULTS

We found a strong association of type 2 diabetes with 1,5-anhydroglucitol (1,5-AG) in saliva (P = 3.6 × 10(-13)). Levels of 1,5-AG in saliva highly correlated with 1,5-AG levels in blood and inversely correlated with blood glucose and glycosylated hemoglobin levels. These findings were robust across three different non-Caucasian ethnicities (Arabs, South Asians, and Filipinos), irrespective of body mass index, age, and gender.

CONCLUSIONS

Clinical studies have already established 1,5-AG in blood as a reliable marker of short-term glycemic control. Our study suggests that 1,5-AG in saliva can be used in national screening programs for undiagnosed diabetes, which are of particular interest for Middle Eastern countries with young populations and exceptionally high diabetes rates.

Elevated HbA1c levels in individuals not diagnosed with type 2 diabetes in Qatar: a pilot study

BACKGROUND

The prevalence of type 2 diabetes (T2D) in Qatar and the Middle East is one of the highest in the world. It is estimated that about one quarter of the individuals with tbl2D are undiagnosed. Elevated HbA1c levels are an indicator of tbl2D or a pre-diabetic state. In this study we set out to examine which factors, such as anthropometric and socio-demographic risk factors, are associated with elevated HbA1c levels in a population without tbl2D.

METHODS

We examined 191 subjects with no record of tbl2D. Anthropometrics and HbA1c were measured. Socio-demographic (age, gender, ethnicity and educational level) and health information were assessed through questionnaires. Elevated HbA1c levels were defined as >6.0% (>42 mmol/mol). Individual risk factors were examined in relationship to having elevated HbA1c levels using logistic regression.

RESULTS

Thirty-eight (20%) study participants had elevated HbA1c levels. Participants from South Asian and Filipino descent were more likely to present with elevated HbA1c levels than Arab participants (adjusted odds ratios (OR): 13.30 (95% confidence interval (CI): 4.24, 41.79), p < 0.001 for South Asian and 4.54 (95% CI: 1.04, 19.83), p = 0.04 for Filipinos). A body mass index of above 30 kg/m(2) was associated with elevated HbA1c levels (adjusted OR: 2.90 (95% CI: 1.29, 6.51), p = 0.01). Neither gender nor educational level was associated with elevated HbA1c levels.

CONCLUSIONS

Elevated HbA1c levels in individuals not diagnosed with diabetes were most frequently found in the South Asian and Filipino immigrant population. Special attention should therefore be given to the early identification of tbl2D in these subjects.

Ethnic and gender differences in advanced glycation end products measured by skin auto-fluorescence

Background

Advanced glycation end products (AGEs) have been shown to be a predictor of cardiovascular risk in Caucasian subjects. In this study we examine whether the existing reference values are useable for non-Caucasian ethnicities. Furthermore, we assessed whether gender and smoking affect AGEs.

Methods

AGEs were determined by a non-invasive method of skin auto-fluorescence (AF). AF was measured in 200 Arabs, 99 South Asians, 35 Filipinos and 14 subjects of other/mixed ethnicity in the Qatar Metabolomics Study on Diabetes (QMDiab). Using multivariate linear regression analysis and adjusting for age and type 2 diabetes, we assessed whether ethnicity, gender and smoking were associated with AF.

Results

The mean AF was 2.27 arbitrary units (AU) (SD: 0.63). Arabs and Filipinos had a significant higher AF than the South Asian population (0.25 arbitrary units (AU) (95% CI: 0.11‒0.39), p = 0.001 and 0.34 (95% CI: 0.13‒0.55), p = 0.001 respectively). Also, AF was significantly higher in females (0.41 AU (95% CI: 0.29‒0.53), p < 0.001). AF associated with smoking (0.21 AU (95% CI: 0.01‒0.41), p = 0.04) and increased with the number of pack-years smoked (p = 0.02).

Conclusions

This study suggests that the existing reference values should take ethnicity, gender and smoking into account. Larger studies in specific ethnicities are necessary to create ethnic- and gender-specific reference values.

Treatment outcome of acne vulgaris with oral isotretinoin

OBJECTIVE

To determine the clinical efficacy of oral isotretinoin in the treatment of severe acne and assess its effect on total serum cholesterol, triglycerides, HDL-cholesterol and Low-Density Lipoprotein-cholesterol (LDL-cholesterol).

STUDY DESIGN

A cohort, descriptive, hospital-based study.

PLACE AND DURATION OF STUDY

Al-Ain Medical District, Tawam Hospital, United Arab Emirates, from 1994 to 2002.

METHODOLOGY

A total of 198 patients seen at Tawam Hospital, referred with acne vulgaris for a minimum of 6 weeks, were treated by isotretinoin for the first time, were included in the study. Variables studied were as per objectives apart from demographics and distribution.

RESULTS

The study included 63 (32%) males and 135 (68%) females of mean age (+/-SD) of 21.3+/-5.6 years. Majority (81%) of patients was under 25 years. Of them, 26 patients had family history of acne. The most common site of acne was on face (66.7%), followed by trunk (26.2%) and neck (9.1%). Of 198 patients treated, 32.8% were cured, 19.1% markedly improved, 11.1% moderately improved and 24.2% of patients were advised for further treatment. There was no marked change in total and LDL-cholesterol, while LDL and triglycerides changed markedly.

CONCLUSION

In acne patients, isotretinoin is effective in producing remission. In addition, it was safe and its effect on serum lipids was transient, especially in healthy and young patients with normal liver functions.

Gonococcal epididymitis

A case of gonococcal epididymitis is discussed. The patient was successfully treated with tetracycline 500 mg orally, every six hours for ten days, with a complete resolution of symptoms.