Review of methods for measuring β-cell function: Design considerations from the Restoring Insulin Secretion (RISE) Consortium

Metformin monotherapy for adults with type 2 diabetes mellitus

BACKGROUND

Worldwide, there is an increasing incidence of type 2 diabetes mellitus (T2DM). Metformin is still the recommended first-line glucose-lowering drug for people with T2DM. Despite this, the effects of metformin on patient-important outcomes are still not clarified.

OBJECTIVES

To assess the effects of metformin monotherapy in adults with T2DM.

SEARCH METHODS

We based our search on a systematic report from the Agency for Healthcare Research and Quality, and topped-up the search in CENTRAL, MEDLINE, Embase, WHO ICTRP, and ClinicalTrials.gov. Additionally, we searched the reference lists of included trials and systematic reviews, as well as health technology assessment reports and medical agencies. The date of the last search for all databases was 2 December 2019, except Embase (searched up 28 April 2017).

SELECTION CRITERIA

We included randomised controlled trials (RCTs) with at least one year's duration comparing metformin monotherapy with no intervention, behaviour changing interventions or other glucose-lowering drugs in adults with T2DM.

DATA COLLECTION AND ANALYSIS

Two review authors read all abstracts and full-text articles/records, assessed risk of bias, and extracted outcome data independently. We resolved discrepancies by involvement of a third review author. For meta-analyses we used a random-effects model with investigation of risk ratios (RRs) for dichotomous outcomes and mean differences (MDs) for continuous outcomes, using 95% confidence intervals (CIs) for effect estimates. We assessed the overall certainty of the evidence by using the GRADE instrument.

MAIN RESULTS

We included 18 RCTs with multiple study arms (N = 10,680). The percentage of participants finishing the trials was approximately 58% in all groups. Treatment duration ranged from one to 10.7 years. We judged no trials to be at low risk of bias on all 'Risk of bias' domains. The main outcomes of interest were all-cause mortality, serious adverse events (SAEs), health-related quality of life (HRQoL), cardiovascular mortality (CVM), non-fatal myocardial infarction (NFMI), non-fatal stroke (NFS), and end-stage renal disease (ESRD). Two trials compared metformin (N = 370) with insulin (N = 454). Neither trial reported on all-cause mortality, SAE, CVM, NFMI, NFS or ESRD. One trial provided information on HRQoL but did not show a substantial difference between the interventions. Seven trials compared metformin with sulphonylureas. Four trials reported on all-cause mortality: in three trials no participant died, and in the remaining trial 31/1454 participants (2.1%) in the metformin group died compared with 31/1441 participants (2.2%) in the sulphonylurea group (very low-certainty evidence). Three trials reported on SAE: in two trials no SAE occurred (186 participants); in the other trial 331/1454 participants (22.8%) in the metformin group experienced a SAE compared with 308/1441 participants (21.4%) in the sulphonylurea group (very low-certainty evidence). Two trials reported on CVM: in one trial no CVM was observed and in the other trial 4/1441 participants (0.3%) in the metformin group died of cardiovascular reasons compared with 8/1447 participants (0.6%) in the sulphonylurea group (very low-certainty evidence). Three trials reported on NFMI: in two trials no NFMI occurred, and in the other trial 21/1454 participants (1.4%) in the metformin group experienced a NFMI compared with 15/1441 participants (1.0%) in the sulphonylurea group (very low-certainty evidence). One trial reported no NFS occurred (very low-certainty evidence). No trial reported on HRQoL or ESRD. Seven trials compared metformin with thiazolidinediones (very low-certainty evidence for all outcomes). Five trials reported on all-cause mortality: in two trials no participant died; the overall RR was 0.88, 95% CI 0.55 to 1.39; P = 0.57; 5 trials; 4402 participants). Four trials reported on SAE, the RR was 0,95, 95% CI 0.84 to 1.09; P = 0.49; 3208 participants. Four trials reported on CVM, the RR was 0.71, 95% CI 0.21 to 2.39; P = 0.58; 3211 participants. Three trial reported on NFMI: in two trials no NFMI occurred and in one trial 21/1454 participants (1.4%) in the metformin group experienced a NFMI compared with 25/1456 participants (1.7%) in the thiazolidinedione group. One trial reported no NFS occurred. No trial reported on HRQoL or ESRD. Three trials compared metformin with dipeptidyl peptidase-4 inhibitors (one trial each with saxagliptin, sitagliptin, vildagliptin with altogether 1977 participants). There was no substantial difference between the interventions for all-cause mortality, SAE, CVM, NFMI and NFS (very low-certainty evidence for all outcomes). One trial compared metformin with a glucagon-like peptide-1 analogue (very low-certainty evidence for all reported outcomes). There was no substantial difference between the interventions for all-cause mortality, CVM, NFMI and NFS. One or more SAEs were reported in 16/268 (6.0%) of the participants allocated to metformin compared with 35/539 (6.5%) of the participants allocated to a glucagon-like peptide-1 analogue. HRQoL or ESRD were not reported. One trial compared metformin with meglitinide and two trials compared metformin with no intervention. No deaths or SAEs occurred (very low-certainty evidence) no other patient-important outcomes were reported. No trial compared metformin with placebo or a behaviour changing interventions. Four ongoing trials with 5824 participants are likely to report one or more of our outcomes of interest and are estimated to be completed between 2018 and 2024. Furthermore, 24 trials with 2369 participants are awaiting assessment.

AUTHORS' CONCLUSIONS

There is no clear evidence whether metformin monotherapy compared with no intervention, behaviour changing interventions or other glucose-lowering drugs influences patient-important outcomes.

Theoretical Modeling of Oral Glucose Tolerance Tests Guides the Interpretation of the Impact of Perinatal Cadmium Exposure on the Offspring's Glucose Homeostasis

Oral glucose tolerance tests, in which the concentration of glucose is monitored in the circulation over 2 h after ingesting a bolus, probe diabetic or pre-diabetic conditions. The resulting glucose curves inform about glucose turnover, insulin production and sensitivity, and other parameters. However, extracting the relevant parameters from a single complex curve is not straightforward. We propose a simple modeling method recapitulating the most salient features of the role of insulin-secreting pancreatic β-cells and insulin sensitive tissues. This method implements four ordinary differential equations with ten parameters describing the time-dependence of glucose concentration, its removal rate, and the circulating and stored insulin concentrations. From the initial parameter set adjusted to a reference condition, fitting is done by minimizing a weighted least-square residual. In doing so, the sensitivity of β-cells to glucose was identified as the most likely impacted function at weaning for the progeny of rats that were lightly exposed to cadmium in the perigestational period. Later in life, after young rats received non-contaminated carbohydrate enriched food, differences are more subtle, but modeling agrees with long-lasting perturbation of glucose homeostasis.

1,5-Anhydroglucitol × glycated hemoglobin A1c/100 as a potential biomarker for islet β-cell function among patients with type 2 diabetes

AIMS

This study aimed to explore the level of and changes in the 1,5-anhydroglucitol × glycated hemoglobin A_1c/100 (AH index, AHI) associated with different glucose metabolism statuses and to evaluate the islet function and insulin sensitivity of patients with type 2 diabetes (T2DM) with different AHI levels.

METHODS

Of the 3562 subjects enrolled in this study, 1697 had T2DM. The disposition index (DI) was the product of islet secretion function and insulin sensitivity-related indexes.

RESULTS

The mean AHI level was 1.0 (0.7-1.3) in the general population, while the mean AHI level in the T2DM group was 0.8 (0.5-1.2), which was significantly lower than that in the impaired glucose regulation and normal glucose tolerance group (both 1.2 (0.9-1.5), both P < 0.01). We further divided patients with T2DM into four subgroups according to the quartile of AHI. The results showed that with the increase in AHI level, the homeostasis model assessment of insulin resistance (HOMA-IR) decreased, while HOMA-β, insulin generation index, insulin sensitivity index, and DI increased (all P_{for trend} < 0.01). Multivariate logistic regression showed that the odds ratios for a low DI for increasing levels of AHI were 1.00, 0.22 (0.16-0.29), 0.16 (0.11-0.22), and 0.09 (0.06-0.13), showing a decreasing trend (P_{for trend} < 0.05).

CONCLUSION

The AHI could reflect the variation in glycemic disorder and the function of islet β cells. The lower the AHI, the worse the glycemic disorder, as well as the islet β-cell function.

Obstructive Sleep Apnea Exacerbates Glucose Dysmetabolism and Pancreatic β-Cell Dysfunction in Overweight and Obese Nondiabetic Young Adults

PURPOSE

This study aimed to investigate the effects of obstructive sleep apnea (OSA) on the pancreatic β-cells dysfunction and their implications in the glucose dysmetabolism of overweight and obese nondiabetic young adults.

MATERIALS AND METHODS

The cross-sectional analysis included 422 subjects (261 males/161 females) with the mean age of 27.77 ± 7.51 years and average body mass index (BMI) of 34.84 ± 5.69 kg/m². All subjects underwent polysomnography (PSG), oral glucose tolerance-insulin releasing test (OGTT-IRT) and serum glycosylated hemoglobin A1 (HbA1c) measurement. The glucose metabolism and pancreatic β-cell function in relation to measures of OSA were determined adjustment for important confounders such as age and sex.

RESULTS

OSA subjects accounted for 54.91% in the normal glucose tolerance (NGT) group and 72.11% in the prediabetes (preDM) group (P =0.001). HbA1c was the highest in the preDM subjects with severe OSA. In the NGT subjects, the 1-h glucose level significantly elevated with the OSA severity, and the homeostasis model assessment-β (HOMA-β) was negatively related to nocturnal mean SpO₂ (P <0.05). In the preDM subjects, HOMA-β, early phase insulinogenic index (∆I₃₀/∆G₃₀), total area under the curve of insulin in 180 min (AUC-I₁₈₀), and the oral disposition index (DI_O) were the lowest in the severe OSA group. DI_O was associated with higher oxygen desaturation index (ODI) and lower nocturnal mean SpO₂, and AUC-I₁₈₀ was negatively related to TS90 (P <0.05).

CONCLUSION

Our study indicated higher prevalence of OSA in overweight and obese nondiabetic young adults, especially preDM subjects. The impaired glucose tolerance was observed early after glucose intake in the NGT subjects. OSA induces compensatory increase in the pancreatic β-cell function in the NGT subjects, while pancreatic β-cell dysfunction is present in the preDM subjects with severe OSA.

Pancreatic β-cell dysfunction in normoglycemic patients and risk factors

AIMS

To evaluate pancreatic β-cell function (βf) in patients with normoglycemia (NG) and normal glucose tolerance (NGT) and related risk factors.

METHODS

An observational and comparative study in 527 patients with NG and NGT that were divided by quartiles of βf according to the disposition index derived from OGTT. Anthropometrical, clinical, nutritional, and biochemical variables were measured and associated with βf.

RESULTS

Quartiles of βf were Q1 = DI < 1.93 n = 131, Q2 = DI 1.93-2.45 n = 134, Q3 = DI 2.46-3.1 n = 133, and Q4 = DI > 3.1 n = 129. There was a progressive reduction in pancreatic β-cell function and it is negatively correlated with age, weight, BMI, total body fat and visceral fat, waist circumference, total cholesterol, LDL, and triglycerides (p < 0.01). Glucose levels during OGTT had a negative correlation with βf; the product of fasting glucose by 1-h glucose had the best correlation with βf (r = 0.611, p < 0.001) and was the best predictor of βdf (AUC 0.816, CI 95% 0.774-0.857), even better than 1-h glucose (r = 0.581, p < 0.001). Energy, fat, and carbohydrate intake were negatively correlated with βf (p < 0.05). Glucose levels at 1-h OGTT > 110 mg/dl were positively associated with pancreatic βdf (OR 6.85, CI 95% 3.86-12.4). In the multivariate analysis, glucose levels during OGTT, fasting insulin, and BMI were the main factors associated with βf.

CONCLUSIONS

A subgroup of patients with NG and NGT may have a loss of 40% of their βf. Factors related to this βdf were age, adiposity, glucose during OGTT, and the product of fasting and 1-h glucose, as well as food intake.

Obesity and insulin sensitivity effects on cardiovascular risk factors: Comparisons of obese dysglycemic youth and adults

BACKGROUND

Obesity and pubertal insulin resistance worsen cardiovascular (CV) risk factors in youth. It is unclear how the relationships of obesity and insulin resistance with CV risk compare to adults.

SUBJECTS AND METHODS

We evaluated 66 pubertal youth (mean ± SD: age 14.2 ± 2.0 years, body mass index [BMI] 36.6 ± 6.0 kg/m² , hemoglobin A1c [HbA1c] 38.5 ± 6.1 mmol/mol) and 355 adults with comparable BMI (age 52.7 ± 9.4 years, BMI 35.1 ± 5.1 kg/m² , HbA1c 39.8 ± 4.2 mmol/mol) participating in a multicenter study. Insulin sensitivity was quantified using hyperglycemic clamps. Assessment of CV risk factors was standardized across sites. Regression analyses compared the impact of insulin sensitivity and CV risk factors between youth and adults.

RESULTS

Obese pubertal youth were more insulin resistant than comparably obese adults (P < .001), but with similar slopes for the inverse relationship between insulin sensitivity and obesity. The impact of obesity on CV risk factors was explained by insulin sensitivity (P = NS after adjustment for sensitivity). The two age groups did not differ in relationships between insulin sensitivity and diastolic blood pressure, total cholesterol, and low-density lipoprotein (LDL) cholesterol, after adjusting for obesity. However, while systolic blood pressure (SBP) and high-density lipoprotein (HDL) cholesterol exhibited the expected direct and inverse relationships, respectively with insulin sensitivity in adults, these slopes were flat in youth across the range of insulin sensitivity (P ≤ .05 for group differences).

CONCLUSIONS

Effects of obesity on CV risk factors were attributable to insulin sensitivity in both groups. The relationships between insulin sensitivity and CV risk factors were similar in obese youth and adult groups except for SBP and HDL cholesterol.

CLINICAL TRIAL REGISTRATION

The RISE consortium studies are registered through Clinicaltrials.gov as NCT01779362 (Adult Medication Study); NCT01763346 (Adult Surgery Study); and NCT01779375 (Pediatric Medication Study). Clinical trial registration numbers: NCT01779362, NCT01779375 and NCT01763346 at clinicaltrials.gov.

Risk Factors Associated With Progression Toward Endocrine Insufficiency in Chronic Pancreatitis

OBJECTIVE

Little data exist describing the change over time in islet function and glycemic control in patients with chronic pancreatitis (CP).

METHODS

In 325 CP patients who underwent 2 mixed meal tolerance tests and/or glycated hemoglobin (HbA1c) levels, we estimated the rate of change in metabolic measures per 6 months and assessed the association between potential risk factors for diabetes and rate of change using multivariate regression models.

RESULTS

Per 6-month time, HbA1c increased by 0.062% with a standard error of 0.029% (P = 0.037) and the ratio (area under the curve (AUC) C-peptide to AUC glucose from mixed meal tolerance testing) decreased by 0.0028 with a standard error of 0.0011 (P = 0.014). We observed more rapid decline in smokers (AUC C-peptide, P = 0.043) and patients with surgical drainage (AUC glucose, P = 0.001; ratio, P = 0.03) or with calcific pancreatitis (HbA1c, P = 0.003). In multivariate models, AUC C-peptide and ratio declined at a greater rate in smokers and HbA1c in those with pancreatic calcifications (both P < 0.05).

CONCLUSIONS

We observed a measurable decline in β-cell function and glycemic control in patients with CP. Patients with a history of tobacco smoking, surgical drainage, or pancreatic calcification may be at highest risk.

The RISE Consortium. Lack of Durable Improvements in β-Cell Function Following Withdrawal of Pharmacological Interventions in Adults With Impaired Glucose Tolerance or Recently Diagnosed Type 2 Diabetes

OBJECTIVE

The Restoring Insulin Secretion (RISE) Adult Medication Study compared pharmacological approaches targeted to improve β-cell function in individuals with impaired glucose tolerance (IGT) or treatment-naive type 2 diabetes of <12 months duration.

RESEARCH DESIGN AND METHODS

A total of 267 adults with IGT (n = 197, 74%) or recently diagnosed type 2 diabetes (n = 70, 26%) were studied. Participants were randomized to receive 12 months of metformin alone, 3 months of insulin glargine with a target fasting glucose <5 mmol/L followed by 9 months of metformin, 12 months of liraglutide combined with metformin, or 12 months of placebo. β-Cell function was assessed using hyperglycemic clamps at baseline, 12 months (on treatment), and 15 months (3 months off treatment). The primary outcome was β-cell function at 15 months compared with baseline.

RESULTS

All three active treatments produced on-treatment reductions in weight and improvements in HbA1c compared with placebo; the greatest reductions were seen in the liraglutide plus metformin group. At 12 months, glucose-stimulated C-peptide responses improved in the three active treatment groups and were greatest in the liraglutide plus metformin group, but the arginine-stimulated incremental C-peptide response was reduced in the liraglutide plus metformin group. Despite on-treatment benefits, 3 months after treatment withdrawal there were no sustained improvements in β-cell function in any treatment group.

CONCLUSIONS

In adults with IGT or recently diagnosed type 2 diabetes, interventions that improved β-cell function during active treatment failed to produce persistent benefits after treatment withdrawal. These observations suggest that continued intervention may be required to alter the progressive β-cell dysfunction in IGT or early type 2 diabetes.

Effects of Treatment of Impaired Glucose Tolerance or Recently Diagnosed Type 2 Diabetes With Metformin Alone or in Combination With Insulin Glargine on β-Cell Function: Comparison of Responses In Youth And Adults

β-Cell dysfunction is central to the pathogenesis of impaired glucose tolerance (IGT) and type 2 diabetes. Compared with adults, youth have hyperresponsive β-cells and their decline in β-cell function appears to be more rapid. However, there are no direct comparisons of β-cell responses to pharmacological intervention between the two age-groups. The Restoring Insulin Secretion (RISE) Adult Medication Study and the RISE Pediatric Medication Study compared interventions to improve or preserve β-cell function. Obese youth (n = 91) and adults (n = 132) with IGT or recently diagnosed type 2 diabetes were randomized to 3 months of insulin glargine followed by 9 months of metformin, or 12 months of metformin. Hyperglycemic clamps conducted at baseline, after 12 months of medication, and 3 months after medication withdrawal assessed β-cell function as steady-state and maximal C-peptide responses adjusted for insulin sensitivity. Temporal changes in β-cell function were distinctly different. In youth, β-cell function deteriorated during treatment and after treatment withdrawal, with no differences between treatment groups. In adults, β-cell function improved during treatment, but this was not sustained after treatment withdrawal. The difference in β-cell function outcomes in response to medications in youth versus adults supports a more adverse trajectory of β-cell deterioration in youth.

Association of Habitual Daily Physical Activity With Glucose Tolerance and β-Cell Function in Adults With Impaired Glucose Tolerance or Recently Diagnosed Type 2 Diabetes From the Restoring Insulin Secretion (RISE) Study

OBJECTIVE

We examined the relationship between habitual daily physical activity and measures of glucose tolerance, insulin sensitivity, and β-cell responses in adults with impaired glucose tolerance (IGT) or drug-naive, recently diagnosed type 2 diabetes.

RESEARCH DESIGN AND METHODS

Participants included 230 adults (mean ± SD age 54.5 ± 8.5 years, BMI 35 ± 5.5 kg/m²; 42.6% women) who underwent a 3-h oral glucose tolerance test (OGTT) and hyperglycemic clamp. Wrist accelerometers worn for 7 consecutive days measured total physical activity counts (TAC) (daily mean 233,460 [∼50th percentile for age]). We evaluated whether TAC was associated with fasting plasma glucose, OGTT 2-h plasma glucose or glucose incremental area under the curve (G-iAUC), hyperglycemic clamp measures of insulin sensitivity (steady-state glucose infusion rate/insulin [M/I]) and β-cell responses (acute C-peptide response to glucose, steady-state C-peptide, and maximal β-cell response), and OGTT C-peptide index (ΔC-peptide_0-30/Δglucose_0-30).

RESULTS

After adjustments for confounders, there was no association of TAC with fasting plasma glucose, 2-h glucose, or G-iAUC. Higher TAC was associated with higher insulin sensitivity (M/I). After adjusting for M/I, higher TAC was not associated with measures of β-cell response.

CONCLUSIONS

In adults with IGT or drug-naive, recently diagnosed type 2 diabetes, higher levels of habitual physical activity are associated with higher insulin sensitivity. Further studies are needed to understand why higher levels of physical activity are not associated with better β-cell response.

Repeatability of the hyperglycaemic clamp for assessment of β-cell response and insulin sensitivity in horses

BACKGROUND

The hyperglycaemic clamp has been used for measurement of insulin sensitivity (IS) but not for measurement of β-cell response in the horse. However, the repeatability of this test has not been reported for horses.

OBJECTIVES

To determine the repeatability and reliability of measures for IS and β-cell response to glucose using the hyperglycaemic clamp in horses.

STUDY DESIGN

Repeated measures, longitudinal study.

METHODS

Six healthy Standardbred mares underwent a 120-min hyperglycaemic clamp on two occasions with a 10-day washout period. Indices of repeatability and reliability were calculated from measures of IS and β-cell response to glucose derived from each hyperglycaemic clamp.

RESULTS

Measures of β-cell response to glucose, including area under the insulin response curve in the time interval 0-120 min and during steady state (60-120 min), as well as the mean insulin concentration during steady state had coefficient of variations (CV) of 9.5, 10.5 and 9.3 respectively and intraclass correlation coefficients (ICC) of 0.93, 0.93 and 0.95 respectively. The measure of glucose disposal (M) had lower CV (12.4) and ICC (0.71) compared to measure of IS (M/I-index; CV of 17.4 and ICC of 0.89).

MAIN LIMITATIONS

The study was conducted in a small number of horses.

CONCLUSIONS

The hyperglycaemic clamp is a diagnostic method for assessing β-cell response to intravenous glucose with high repeatability and reliability. Insulin sensitivity can be determined with the same test but the repeatability for these measurements is lower compared to the measurements for β-cell response.

Glucose metabolism in patients with psoriasis

BACKGROUND

Epidemiological studies strongly suggest that psoriasis predisposes to type 2 diabetes. Several theories have been proposed to explain how these disease entities might be pathophysiologically connected.

OBJECTIVES

Our primary objective was to elucidate whether clinical data support the notion of common pathophysiological denominators in patients with psoriasis and type 2 diabetes, and thus to delineate the association between the two conditions that has arisen on the basis of epidemiological studies.

METHODS

We reviewed clinical studies investigating parameters of glucose metabolism in patients with psoriasis. The PubMed and Embase databases were searched for studies investigating glucose metabolism in adult patients with psoriasis as a primary or secondary end point. Studies had to include a relevant control group.

RESULTS

Twenty-six clinical studies reporting on insulin resistance, glucose tolerance or insulin secretion were eligible for review. The results were widely conflicting, with less than half of the studies showing results suggestive of defective glucose metabolism in patients with psoriasis. In general, the studies suffered from a lack of information regarding possible confounders and patient characteristics. Furthermore, the research methods varied, and in all but one study they might not have been appropriate to detect early and subtle defects in glucose metabolism.

CONCLUSIONS

The available literature does not unequivocally support common pathophysiological denominators in psoriasis and type 2 diabetes. Well-designed clinical studies are needed to expose potential diabetogenic defects in the glucose metabolism in patients with psoriasis.

Impact of Gastric Banding Versus Metformin on β-Cell Function in Adults With Impaired Glucose Tolerance or Mild Type 2 Diabetes

OBJECTIVE

Type 2 diabetes (T2D) results from progressive loss of β-cell function. The BetaFat study compared gastric banding and metformin for their impact on β-cell function in adults with moderate obesity and impaired glucose tolerance (IGT) or recently diagnosed, mild T2D.

RESEARCH DESIGN AND METHODS

Eighty-eight people aged 21-65 years, BMI 30-40 kg/m², with IGT or diabetes known for <1 year, were randomized to gastric banding or metformin for 2 years. Hyperglycemic clamps (11.1 mmol/L) followed by arginine injection at maximally potentiating glycemia (>25 mmol/L) were performed at baseline, 12 months, and 24 months to measure steady-state C-peptide (SSCP) and acute C-peptide response to arginine at maximum glycemic potentiation (ACPRmax) and insulin sensitivity (M/I).

RESULTS

At 24 months, the band group lost 10.7 kg; the metformin group lost 1.7 kg (P < 0.01). Insulin sensitivity increased 45% in the band group and 25% in the metformin group (P = 0.30 between groups). SSCP adjusted for insulin sensitivity fell slightly but not significantly in each group (P = 0.34 between groups). ACPRmax adjusted for insulin sensitivity fell significantly in the metformin group (P = 0.002) but not in the band group (P = 0.25 between groups). HbA_1c fell at 12 and 24 months in the band group (P < 0.004) but only at 12 months (P < 0.01) in the metformin group (P > 0.14 between groups). Normoglycemia was present in 22% and 15% of band and metformin groups, respectively, at 24 months (P = 0.66 between groups).

CONCLUSIONS

Gastric banding and metformin had similar effects to preserve β-cell function and stabilize or improve glycemia over a 2-year period in moderately obese adults with IGT or recently diagnosed, mild T2D.

The RISE Consortium, Nadeau KJ, Hannon TS, Edelstein SL, Arslanian SA, Caprio S, Leschek EW, Zeitler PS, Buchanan TA, Ehrmann DA, Mather KJ, Kahn SE, Gross S, Williams J, Cree-Green M, Reyes YG, Vissat K, Brown K, Guerra N, Porter K, Savoye M, Pierpont B, Garrett T, Lteif A, Patel A, Chisholm R, Moore K, Pirics V, Pratt L, Temple KA, Rue A, Barengolts E, Mokhlesi B, Van Cauter E, Sam S, Miller MA, Atkinson KM, Palmer JP, Utzschneider KM, Gebremedhin T, Kernan-Schloss A, Kozedub A, Montgomery BK, Morse EJ, Xiang AH, Trigo E, Beale E, Hendee FN, Katkhouda N, Nayak K, Martinez M, Montgomery C, Wang X, Lachin JM, Hogan AN, Marcovina S, Harting J, Albers J, Hill D, Savage PJ. Impact of Insulin and Metformin Versus Metformin Alone on β-Cell Function in Youth With Impaired Glucose Tolerance or Recently Diagnosed Type 2 Diabetes

OBJECTIVE

Pediatric type 2 diabetes prevalence is increasing, with β-cell dysfunction key in its pathogenesis. The RISE Pediatric Medication Study compared two approaches-glargine followed by metformin and metformin alone-in preserving or improving β-cell function in youth with impaired glucose tolerance (IGT) or recently diagnosed type 2 diabetes during and after therapy withdrawal.

RESEARCH DESIGN AND METHODS

Ninety-one pubertal, overweight/obese 10-19-year-old youth with IGT (60%) or type 2 diabetes of <6 months duration (40%) were randomized to either 3 months of insulin glargine with a target glucose of 4.4-5.0 mmol/L followed by 9 months of metformin or to 12 months of metformin alone. β-Cell function (insulin sensitivity paired with β-cell responses) was assessed by hyperglycemic clamp at baseline, 12 months (on treatment), and 15 months (3 months off treatment).

RESULTS

No significant differences were observed between treatment groups at baseline, 12 months, or 15 months in β-cell function, BMI percentile, HbA_1c, fasting glucose, or oral glucose tolerance test 2-h glucose results. In both treatment groups, clamp-measured β-cell function was significantly lower at 12 and 15 months versus baseline. HbA_1c fell transiently at 6 months within both groups. BMI was higher in the glargine followed by metformin versus metformin alone group between 3 and 9 months. Only 5% of participants discontinued the interventions, and both treatments were well tolerated.

CONCLUSIONS

In youth with IGT or recently diagnosed type 2 diabetes, neither 3 months of glargine followed by 9 months of metformin nor 12 months of metformin alone halted the progressive deterioration of β-cell function. Alternate approaches to preserve β-cell function in youth are needed.

Methods for Measuring Risk for Type 2 Diabetes in Youth: the Oral Glucose Tolerance Test (OGTT)

PURPOSE OF REVIEW

The oral glucose tolerance test (OGTT) is used both in clinical practice and research to assess glucose tolerance. In addition, the OGTT is utilized for surrogate measures of insulin sensitivity and the insulin response to enteral glucose and has been widely applied in the evaluation of β-cell dysfunction in obesity, prediabetes, and type 2 diabetes. Here we review the use of the OGTT and the OGTT-derived indices for measurement of risk markers for type 2 diabetes in youth.

RECENT FINDINGS

Advantages of using the OGTT for measures of diabetes risk include its accessibility and the incorporation of physiological contributions of the gut-pancreas axis in the measures of insulin response to glucose. Mathematical modeling expands the potential gains from the OGTT in physiology and clinical research. Disadvantages include individual differences in the rate of glucose absorption that modify insulin responses, imperfect control of the glycemic stimulus, and poor intraindividual reproducibility. Available research suggests the OGTT provides valuable information about the development of impaired glycemic control and β-cell function in obese youth along the spectrum of glucose tolerance.

Abdominal Subcutaneous Fat: A Favorable or Nonfunctional Fat Depot for Glucose Metabolism in Chinese Adults?

OBJECTIVE

The objective of this study was to assess the associations of abdominal visceral and subcutaneous adipose tissue with blood glucose and beta-cell function.

METHODS

In this study, 11,223 participants without known diabetes were selected for this cross-sectional analysis. Visceral and subcutaneous fat area (VFA and SFA) were measured by magnetic resonance imaging. An oral glucose tolerance test was conducted, and beta-cell function was evaluated.

RESULTS

Men had significantly larger VFA but smaller SFA than women. After controlling for age, linear regression showed that SFA was adversely associated with 0-minute, 30-minute, and 2-hour plasma glucose (PG) and early-, first- and second-phase disposition indices (DIs). After further adjustment for BMI and VFA, some associations of SFA with PG indices and DIs disappeared, while the other associations became significantly weaker in men (2-hour PG: 0.05 and DI_2nd : -0.05) or were reversed in women (0-minute, 30-minute, and 2-hour PG: from -0.07 to -0.04; DI_1st : 0.04, P < 0.05). After adjustment for age, BMI, and SFA, VFA was significantly and adversely associated with PG indices and DIs, with the largest standardized regression coefficients with 2-hour PG.

CONCLUSIONS

The associations of SFA with blood glucose and beta-cell function were clinically insignificant in Chinese adults. VFA had the strongest association with 2-hour PG.

Vitamin D supplementation and non-alcoholic fatty liver disease: A critical and systematic review of clinical trials

Previous observational studies have found a relationship between vitamin D deficiency and non-alcoholic fatty liver disease (NAFLD). However, this type of study could not show the causal relationship between these two conditions. Therefore, we systematically and critically reviewed the available clinical trials to elucidate such relationship. We searched databases such as Medline, Scopus and Cochrane to identify the clinical trials that assessed the effects of vitamin D supplementation in adults with NAFLD. The outcome variables of interest were indicators of hepatic steatosis, liver enzymes, insulin resistance, inflammation and oxidative stress. A total of 6 studies were included in the qualitative analysis. Only in two studies the grade of hepatic steatosis decreased significantly after vitamin D supplementation. The changes in insulin resistance parameters were reported significant only in one. Of the 3 included studies that measured biomarkers of inflammation and oxidative stress, one revealed a significant decrease in these biomarkers after vitamin D supplementation. Findings from current review study provided new insight into the factors that could affect the therapeutic role of vitamin D in NAFLD. Factors such as gender differences, baseline serum status of vitamin D, co-supplementation with calcium and gene polymorphism should be considered when designing future clinical trials.