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OBJECTIVE In type 2 diabetes, insulin resistance and progressive β-cell failure require treatment with high insulin doses, leading to weight gain. Our aim was to study whether a three-meal diet (3Mdiet) with a carbohydrate-rich breakfast may upregulate clock gene expression and, as a result, allow dose reduction of insulin, leading to weight loss and better glycemic control compared with an isocaloric six-meal diet (6Mdiet). RESEARCH DESIGN AND METHODS Twenty-eight volunteers with diabetes (BMI 32.4 ± 5.2 kg/m2 and HbA1c 8.1 ± 1.1% [64.5 ± 11.9 mmol/mol]) were randomly assigned to 3Mdiet or 6Mdiet. Body weight, glycemic control, continuous glucose monitoring (CGM), appetite, and clock gene expression were assessed at baseline, after 2 weeks, and after 12 weeks. RESULTS 3Mdiet, but not 6Mdiet, led to a significant weight loss (−5.4 ± 0.9 kg) (P < 0.01) and decreased HbA1c (−12 mmol/mol [−1.2%]) (P < 0.0001) after 12 weeks. Fasting glucose and daily and nocturnal glucose levels were significantly lower on the 3Mdiet. CGM showed a significant decrease in the time spent in hyperglycemia only on the 3Mdiet. Total daily insulin dose was significantly reduced by 26 ± 7 units only on the 3Mdiet. There was a significant decrease in the hunger and cravings only in the 3Mdiet group. Clock genes exhibited oscillation, increased expression, and higher amplitude on the 3Mdiet compared with the 6Mdiet. CONCLUSIONS A 3Mdiet, in contrast to an isocaloric 6Mdiet, leads to weight loss and significant reduction in HbA1c, appetite, and overall glycemia, with a decrease in daily insulin. Upregulation of clock genes seen in this diet intervention could contribute to the improved glucose metabolism.

OBJECTIVE The circadian clock regulates glucose metabolism by mediating the activity of metabolic enzymes, hormones, and transport systems. Breakfast skipping and night eating have been associated with high HbA1c and postprandial hyperglycemia after lunch and dinner. Our aim was to explore the acute effect of breakfast consumption or omission on glucose homeostasis and clock gene expression in healthy individuals and individuals with type 2 diabetes. RESEARCH DESIGN AND METHODS In a crossover design, 18 healthy volunteers and 18 volunteers with 14.5 ± 1.5 years diabetes, BMI 30.7 ± 1.1 kg/m2, and HbA1c 7.6 ± 0.1% (59.6 ± 0.8 mmol/mol) were randomly assigned to a test day with breakfast and lunch (YesB) and a test day with only lunch (NoB). Postprandial clock and clock-controlled gene expression, plasma glucose, insulin, intact glucagon-like peptide 1 (iGLP-1), and dipeptidyl peptidase IV (DPP-IV) plasma activity were assessed after breakfast and lunch. RESULTS In healthy individuals, the expression level of Per1, Cry1, Rorα, and Sirt1 was lower (P < 0.05) but Clock was higher (P < 0.05) after breakfast. In contrast, in individuals with type 2 diabetes, Per1, Per2, and Sirt1 only slightly, but significantly, decreased and Rorα increased (P < 0.05) after breakfast. In healthy individuals, the expression level of Bmal1, Rorα, and Sirt1 was higher (P < 0.05) after lunch on YesB day, whereas the other clock genes remained unchanged. In individuals with type 2 diabetes, Bmal1, Per1, Per2, Rev-erbα, and Ampk increased (P < 0.05) after lunch on the YesB day. Omission of breakfast altered clock and metabolic gene expression in both healthy and individuals with type 2 diabetes. CONCLUSIONS Breakfast consumption acutely affects clock and clock-controlled gene expression leading to normal oscillation. Breakfast skipping adversely affects clock and clock-controlled gene expression and is correlated with increased postprandial glycemic response in both healthy individuals and individuals with diabetes.

OBJECTIVE Counterregulatory responses are critical to prevent hypoglycemia in subjects with type 2 diabetes. This is particularly important in insulin-treated patients. This study explored the effect of the glucagon-like peptide 1 receptor agonist lixisenatide on the hormonal counterregulatory responses to insulin-induced hypoglycemia when added to basal insulin therapy in subjects with type 2 diabetes. RESEARCH DESIGN AND METHODS The study was a single-center, double-blind, randomized, placebo-controlled crossover study involving 18 subjects with type 2 diabetes (11 males) with a mean age of 55 years, diabetes duration of 12 years, HbA1c level of 7.7%, fasting blood glucose (FBG) concentration of 9.7 mmol/L, and a BMI of 33 kg/m2, who were treated with basal insulin (mean duration 7 years, daily dose 39 units/day) and metformin (mean daily dose 2.1 g). Subjects received treatment with lixisenatide or placebo for 6 weeks in random order, with a 4-week washout period in between. After 6 weeks of treatment, subjects underwent a two-step hyperinsulinemic hypoglycemic clamp at 3.5 and 2.8 mmol/L. RESULTS After 6 weeks of treatment, HbA1c and FBG levels were lower after lixisenatide therapy than after placebo therapy. At the hypoglycemic level of 3.5 mmol/L, glucagon and epinephrine levels were significantly lower during lixisenatide treatment than during placebo treatment, whereas at 2.8 mmol/L glucagon and epinephrine levels did not differ between the subjects. Cortisol, pancreatic polypeptide, and norepinephrine levels did not differ significantly between the treatments. CONCLUSIONS Glucagon and epinephrine levels are reduced by lixisenatide at a concentration of 3.5 mmol/L, but their counterregulatory responses to deep hypoglycemia at a concentration of 2.8 mmol/L are sustained during treatment with lixisenatide in combination with basal insulin.

OBJECTIVE Skipping breakfast has been consistently associated with high HbA1c and postprandial hyperglycemia (PPHG) in patients with type 2 diabetes. Our aim was to explore the effect of skipping breakfast on glycemia after a subsequent isocaloric (700 kcal) lunch and dinner. RESEARCH DESIGN AND METHODS In a crossover design, 22 patients with diabetes with a mean diabetes duration of 8.4 ± 0.7 years, age 56.9 ± 1.0 years, BMI 28.2 ± 0.6 kg/m2, and HbA1c 7.7 ± 0.1% (61 ± 0.8 mmol/mol) were randomly assigned to two test days: one day with breakfast, lunch, and dinner (YesB) and another with lunch and dinner but no breakfast (NoB). Postprandial plasma glucose, insulin, C-peptide, free fatty acids (FFA), glucagon, and intact glucagon-like peptide-1 (iGLP-1) were assessed. RESULTS Compared with YesB, lunch area under the curves for 0–180 min (AUC0–180) for plasma glucose, FFA, and glucagon were 36.8, 41.1, and 14.8% higher, respectively, whereas the AUC0-180 for insulin and iGLP-1 were 17% and 19% lower, respectively, on the NoB day (P < 0.0001). Similarly, dinner AUC0-180 for glucose, FFA, and glucagon were 26.6, 29.6, and 11.5% higher, respectively, and AUC0-180 for insulin and iGLP-1 were 7.9% and 16.5% lower on the NoB day compared with the YesB day (P < 0.0001). Furthermore, insulin peak was delayed 30 min after lunch and dinner on the NoB day compared with the YesB day. CONCLUSIONS Skipping breakfast increases PPHG after lunch and dinner in association with lower iGLP-1 and impaired insulin response. This study shows a long-term influence of breakfast on glucose regulation that persists throughout the day. Breakfast consumption could be a successful strategy for reduction of PPHG in type 2 diabetes.

OBJECTIVE GLP-1 receptor agonists may provide an alternative to prandial insulin for advancing basal insulin therapy. Harmony 6 was a randomized, open-label, active-controlled trial testing once-weekly albiglutide vs. thrice-daily prandial insulin lispro as an add-on to titrated once-daily insulin glargine. RESEARCH DESIGN AND METHODS Patients taking basal insulin (with or without oral agents) with HbA1c 7–10.5% (53–91 mmol/mol) entered a glargine standardization period, followed by randomization to albiglutide, 30 mg weekly (n = 282), subsequently uptitrated to 50 mg, if necessary, or thrice-daily prandial lispro (n = 281) while continuing metformin and/or pioglitazone. Glargine was titrated to fasting plasma glucose of RESULTS At week 26, HbA1c decreased from baseline by −0.82 ± SE 0.06% (9.0 mmol/mol) with albiglutide and −0.66 ± 0.06% (7.2 mmol/mol) with lispro; treatment difference, −0.16% (95% CI −0.32 to 0.00; 1.8 mmol/mol; P < 0.0001), meeting the noninferiority end point (margin, 0.4%). Weight decreased with albiglutide but increased with lispro (−0.73 ± 0.19 kg vs. +0.81 ± 0.19 kg). The mean glargine dose increased from 47 to 53 IU (albiglutide) and from 44 to 51 IU (lispro). Adverse events for albiglutide versus lispro included severe hypoglycemia (0 vs. 2 events), documented symptomatic hypoglycemia (15.8% vs. 29.9%), nausea (11.2% vs. 1.4%), vomiting (6.7% vs. 1.4%), and injection site reactions (9.5% vs. 5.3%). CONCLUSIONS Weekly albiglutide is a simpler therapeutic option than thrice-daily lispro for advancing basal insulin glargine therapy, resulting in comparable HbA1c reduction with weight loss and lower hypoglycemia risk.

OBJECTIVE To examine the efficacy and safety of lixisenatide (20 μg once daily, administered before the morning or evening meal) as add-on therapy in patients with type 2 diabetes insufficiently controlled with metformin alone. RESEARCH DESIGN AND METHODS This was a 24-week, randomized, double-blind, placebo-controlled study in 680 patients with inadequately controlled type 2 diabetes (HbA1c 7–10% [53−86 mmol/mol]). Patients were randomized to lixisenatide morning (n = 255), lixisenatide evening (n = 255), placebo morning (n = 85), or placebo evening (n = 85) injections. RESULTS Lixisenatide morning injection significantly reduced mean HbA1c versus combined placebo (mean change −0.9% [9.8 mmol/mol] vs. −0.4% [4.4 mmol/mol]; least squares [LS] mean difference vs. placebo −0.5% [5.5 mmol/mol], P < 0.0001). HbA1c was significantly reduced by lixisenatide evening injection (mean change –0.8% [8.7 mmol/mol] vs. –0.4% [4.4 mmol/mol]; LS mean difference –0.4% [4.4 mmol/mol], P < 0.0001). Lixisenatide morning injection significantly reduced 2-h postprandial glucose versus morning placebo (mean change −5.9 vs. −1.4 mmol/L; LS mean difference −4.5 mmol/L, P < 0.0001). LS mean difference in fasting plasma glucose was significant in both morning (–0.9 mmol/L, P < 0.0001) and evening (–0.6 mmol/L, P = 0.0046) groups versus placebo. Mean body weight decreased to a similar extent in all groups. Rates of adverse events were 69.4% in both lixisenatide groups and 60.0% in the placebo group. Rates for nausea and vomiting were 22.7 and 9.4% for lixisenatide morning and 21.2 and 13.3% for lixisenatide evening versus 7.6 and 2.9% for placebo, respectively. Symptomatic hypoglycemia occurred in 6, 13, and 1 patient for lixisenatide morning, evening, and placebo, respectively, with no severe episodes. CONCLUSIONS In patients with type 2 diabetes inadequately controlled on metformin, lixisenatide 20 μg once daily administered in the morning or evening significantly improved glycemic control, with a pronounced postprandial effect, and was well tolerated.

The enzyme dipeptidyl peptidase-4 (DPP-4) prevents the inactivation of glucagon-like peptide-1 (GLP-1). Since GLP-1–based therapy is a promising novel treatment of type 2 diabetes, the strategy to inhibit the enzyme has been explored. Several DPP-4 inhibitors are in clinical development; these are orally active and increase levels of active GLP-1, which in turn increases insulin secretion and reduces glucagon secretion and thereby lowers glucose levels. Most experience exists for sitagliptin (Merck) and vildagliptin (Novartis), which both have a long duration of action, allowing once-daily administration. In drug-naive subjects with type 2 diabetes, both sitagliptin and vildagliptin reduce A1C levels by ∼1% as monotherapy, as demonstrated in studies up to 52 weeks. Also in combination with metformin and thiazolidinediones, sitagliptin and vildagliptin improve glycemic control with reduction of A1C of ∼1%. Both sitagliptin and vildagliptin are safe and tolerable with low risk of hypoglycemia. They are both body weight neutral. The studies presented thus far therefore suggest that DPP-4 inhibition is an efficient treatment of type 2 diabetes, both as monotherapy and combination therapy. Because of its efficiency, safety, and tolerability in association with the oral mode of administration, it is expected that DPP-4 inhibition will be a first-line treatment of the early stage of type 2 diabetes, particularly in combination with metformin or thiazolidinediones. GLP-1 is one of the important incretin hormones; it is released after meal ingestion and stimulates insulin secretion (1). GLP-1 also exhibits strong antidiabetic actions, as initially demonstrated already in the early 1990s (2–4). Thus, infusion of GLP-1 lowers circulating glucose through a combination of stimulation of insulin secretion and inhibition of glucagon secretion. A 6-week study with continuous subcutaneous infusion of GLP-1 showed reduction in fasting and prandial glycemia along with reduction in A1C and improvement both in insulin secretion and insulin action …

OBJECTIVE—To assess the 12- and 52-week efficacy of the dipeptidyl peptidase IV inhibitor LAF237 versus placebo in patients with type 2 diabetes continuing metformin treatment. RESEARCH DESIGN AND METHODS—We conducted a 12-week, randomized, double-blind, placebo-controlled trial in 107 patients with type 2 diabetes with a 40-week extension in those completing the core study and agreeing, together with the investigator, to extend treatment to 1 year. Placebo (n = 51) or LAF237 (50 mg once daily, n = 56) was added to ongoing metformin treatment (1,500–3,000 mg/day). HbA1c and fasting plasma glucose (FPG) were measured periodically, and standardized meal tests were performed at baseline, week 12, and week 52. RESULTS—In patients randomized to LAF237, baseline HbA1c averaged 7.7 ± 0.1% and decreased at week 12 (Δ = −0.6 ± 0.1%), whereas HbA1c did not change from a baseline of 7.9 ± 0.1% in patients given placebo (between-group difference in ΔHbA1c = −0.7 ± 0.1%, P < 0.0001). Mean prandial glucose and FPG were significantly reduced in patients receiving LAF237 versus placebo by 2.2 ± 0.4 mmol/l (P < 0.0001) and 1.2 ± 0.4 mmol/l (P = 0.0057), respectively, but plasma insulin levels were not affected. At end point of the extension, the between-group differences in change in mean prandial glucose, insulin, and FPG were −2.4 ± 0.6 mmol/l (P = 0.0001), 40 ± 16 pmol/l (P = 0.0153), and −1.1 ± 0.5 mmol/l (P = 0.0312), respectively. HbA1c did not change from week 12 to week 52 in LAF237-treated patients (n = 42) but increased in participants given placebo (n = 29). The between-group difference in ΔHbA1c after 1 year was −1.1 ± 0.2% (P < 0.0001). CONCLUSIONS—Data from this study demonstrate that LAF237 effectively prevents deterioration of glycemic control when added to metformin monotherapy in type 2 diabetes.

OBJECTIVE—Glucagon-like peptide-1 (GLP-1) has been proposed as a new treatment modality for type 2 diabetes. To circumvent the drawback of the short half-life of GLP-1, inhibitors of the GLP-1–degrading enzyme dipeptidyl peptidase IV (DPP IV) have been examined. Such inhibitors improve glucose tolerance in insulin-resistant rats and mice. In this study, we examined the 4-week effect of 1-[[[2-[(5-cyanopyridin-2-yl)amino]ethyl]amino]acetyl]-2-cyano-(S)-pyrrolidine (NVP DPP728), a selective, orally active inhibitor of DPP IV, in subjects with diet-controlled type 2 diabetes in a placebo-controlled double-blind multicenter study. RESEARCH DESIGN AND METHODS—A total of 93 patients (61 men and 32 women), aged 64 ± 9 years (means ± SD) and with BMI 27.3 ± 2.7 kg/m2, entered the study. Fasting blood glucose was 8.5 ± 1.5 mmol/l, and HbA1c was 7.4 ± 0.7%. Before and after treatment with NVP DPP728 at 100 mg × 3 (n = 31) or 150 mg × 5 (n = 32) or placebo (n = 30), subjects underwent a 24-h study with standardized meals (total 2,000 kcal). RESULTS—Compared with placebo, NVP DPP728 at 100 mg t.i.d. reduced fasting glucose by 1.0 mmol/l (mean), prandial glucose excursions by 1.2 mmol/l, and mean 24-h glucose levels by 1.0 mmol/l (all P < 0.001). Similar reductions were seen in the 150-mg b.i.d. treatment group. Mean 24-h insulin was reduced by 26 pmol/l in both groups (P = 0.017 and P = 0.023). Although not an efficacy parameter foreseen in the study protocol, HbA1c was reduced to 6.9 ± 0.7% in the combined active treatment groups (P < 0.001). Laboratory safety and tolerability was good in all groups. CONCLUSIONS—We conclude that inhibition of DPP IV is a feasible approach to the treatment of type 2 diabetes in the early stage of the disease.

OBJECTIVE—To investigate whether features of the insulin resistance syndrome are associated with altered incretin responses to food intake. RESEARCH DESIGN AND METHODS—From a population-based study, 35 men were recruited, representing a wide spectrum of insulin sensitivity and body weight. Each subject underwent a hyperinsulinemic-euglycemic clamp to determine insulin sensitivity. A mixed meal was given, and plasma levels of gastric inhibitory polypeptide (GIP) and glucagon-like peptide 1 (GLP-1), as well as insulin, glucagon, and glucose were measured. RESULTS—Insulin resistance was associated with impaired GIP and GLP-1 responses to a mixed meal. The total area under the curve (AUC) of the GIP response after the mixed meal was associated with insulin sensitivity (r = 0.54, P < 0.01). There was a significant difference between the highest and the lowest tertile of insulin sensitivity (P < 0.05). GLP-1 levels 15 min after food intake were significantly lower in the most insulin-resistant tertile compared with the most insulin-sensitive tertile. During the first hour, the AUC of GLP-1 correlated significantly with insulin sensitivity (r = 0.47, P < 0.01). Multiple linear regression analysis showed that insulin resistance, but not obesity, was an independent predictor of these decreased incretin responses. CONCLUSIONS—In insulin resistance, the GIP and GLP-1 responses to a mixed meal are impaired and are related to the degree of insulin resistance. Decreased incretin responsiveness may be of importance for the development of impaired glucose tolerance.

OBJECTIVE To determine if the dipeptidyl peptidase-4 inhibitor vildagliptin more effectively inhibits glucagon levels than the sulfonylurea glimepiride during a meal. RESEARCH DESIGN AND METHODS Glucagon responses to a standard meal were measured at baseline and study end point (mean 1.8 years) in a trial evaluating add-on therapy to metformin with 50 mg vildagliptin b.i.d. compared with glimepiride up to 6 mg q.d. in type 2 diabetes (baseline A1C 7.3 ± 0.6%). RESULTS A1C and prandial glucose area under the curve (AUC)0–2 h were reduced similarly in both groups, whereas prandial insulin AUC0–2 h increased to a greater extent by glimepiride. Prandial glucagon AUC0–2 h (baseline 66.6 ± 2.3 pmol · h−1 · l−1) decreased by 3.4 ± 1.6 pmol · h−1 · l−1 by vildagliptin (n = 137) and increased by 3.8 ± 1.7 pmol · h−1 · l−1 by glimepiride (n = 121). The between-group difference was 7.3 ± 2.1 pmol · h−1 · l−1 (P < 0.001). CONCLUSIONS Vildagliptin therapy but not glimepiride improves postprandial α-cell function, which persists for at least 2 years.

It is known that ethnicity is a risk factor for diabetes. Thus, individuals of African, Latin American, and Asian descent are particularly susceptible (1). As an example, a health survey in six urban areas in Peru found a diabetes prevalence of 17% among women (2,3). It was also found that low socioeconomic status was associated with a high burden of noncommunicable diseases and appeared as an independent risk factor for diabetes. In several populations, it is known that increased physical activity reduces the risk for diabetes (4,5). Whether this applies for all populations is, however, not known. The aim of the present study was to explore if supervised endurance training is feasible among socioeconomically marginalized women of a poor urban area in Lima, Peru. The study population consisted of 142 Amerindian women. They were all examined in 1999 (6) and had a normal fasting plasma glucose concentration (range 2.8–5.6 mmol/l). Five years later, a total of 83 women participated in a follow-up examination (7). Of these, 76 consented to take part in the present training study. Mean age was 41 years (range 25–64 years). The women were randomly assigned into group A (one training session per week) or group B (three training sessions per week). No economic compensation was given besides free athlete suits …

OBJECTIVE To examine the absorption of glucagon-like peptide (GLP)-1(7-36) amide from the buccal mucosa of type 2 diabetic patients. Previously, the effects of the peptide have been studied following intravenous and subcutaneous injection. Now, a mucoadhesive, biodegradable buccal GLP-1 tablet (9 mm) containing 119 nmol has been developed as a possible alternative to injection. RESEARCH DESIGN AND METHODS A total of 10 type 2 diabetic patients received a single tablet under fasting conditions and before a standard meal in this randomized placebo-controlled study. RESULTS The mean peak GLP-1 concentration was 125.1 pmol/l and occurred 30 min after application. The mean placebo-adjusted area under the curve was 5,334 min pmol/l, consistent with a relative bioavailability of 6% vs. intravenous injection and 42% vs. subcutaneous injection. The half-life of total peptide activity after buccal administration was 17 min. The placebo-adjusted glucose concentrations decreased by 1.4 mmol/l in fasting experiments and by 4.2 mmol/l after a standard mixed meal. In the fasting state at 30 min, plasma insulin increased by 185% and glucagon decreased by 20%, consistent with the increase in plasma GLP-1 concentrations. The peptide exerted a significant insulinotropic effect during meals (calculated as an insulinogenic index, 0–120 min; 84.1 vs. 45.7 in placebo experiments). CONCLUSIONS Potentially therapeutic plasma levels of GLP-1 were achieved after administration of a single buccal tablet in type 2 diabetic patients. The peptide had a marked glucose-lowering effect during the first 2 h. This new GLP-1 tablet may become a feasible alternative treatment for type 2 diabetic patients, although a more prolonged pharmacokinetic profile is required.

OBJECTIVE Low sex hormone–binding globulin (SHBG) has been proposed as a risk factor for NIDDM development in women. Our aim was to study the relationship between SHBG and androgen activity and glucose tolerance, as well as insulin sensitivity, in women with impaired glucose tolerance (IGT). RESEARCH DESIGN AND METHODS We studied 22 women with IGT and 46 women with normal glucose tolerance (NGT) aged 57–59 years. Free testosterone (androgen activity) was determined as the testosterone-to-SHBG ratio. A World Health Organization 75-g oral glucose tolerance test (OGTT) was performed, and insulin sensitivity was measured with a euglycemic-hyperinsulinemic clamp. RESULTS Fasting glucose (P = 0.021), 2-h blood glucose after the OGTT (P < 0.001), and fasting insulin (P = 0.009) were higher in the IGT group, while insulin sensitivity did not differ significantly between the two groups (P = 0.065). We found that SHBG levels were lower in the IGT group (P = 0.004), while the testosterone-to-SHBG ratio was higher in the IGT than in the NGT group (P = 0.004). Insulin sensitivity correlated negatively with testosterone-to-SHBG ratio in both groups. The correlation was higher in the IGT (r = −0.67, P = 0.001) than in the NGT group (r = −0.29, P = 0.047). In contrast, the 2-h blood glucose correlated with testosterone-to-SHBG ratio in the IGT (r = 0.66, P = 0.001) but not the NGT group (r = −0.04, NS). CONCLUSIONS Postmenopausal women with IGT have higher androgen activity than women with NGT, and the androgen activity correlates with the degree of glucose intolerance in IGT. Furthermore, in women with IGT, who have a high risk of NIDDM development, androgen activity seems to have an enhanced negative influence on insulin sensitivity. Therefore, androgen activity appears to be a risk factor for IGT.

OBJECTIVE—This study evaluated insulin secretion and insulin sensitivity in healthy subjects with normal fasting glucose. RESEARCH DESIGN AND METHODS—A total of 148 healthy women (aged 53–70 years) underwent a glucose-dependent arginine stimulation test and a 2-h euglycemic-hyperinsulinemic clamp. In the arginine test, arginine (5 g) was injected intravenously under baseline (fasting) conditions and after raising the glucose levels to 15 and >28 mmol/l. From this test, the acute insulin response (AIR) to arginine during the three glucose levels (AIR1, AIR2, and AIR3) were estimated. The subjects were divided into quartiles of fasting glucose (n = 37 in each group [range RESULTS—The results show that 1) AIR1 was higher in subjects in the two highest quartiles (P = 0.004), 2) AIR3 was higher in the quartile with the highest fasting glucose (P = 0.012), and 3) insulin sensitivity was reduced in subjects in the highest quartile (P = 0.026) compared with the lower quartiles. The results also show, in contrast, that AIR2 did not show a similar trend to be increased at higher fasting glucose. CONCLUSIONS—It is concluded that 1) raised fasting glucose (albeit still within normal values) augments baseline and maximal arginine-induced insulin secretion in healthy subjects, and 2) this is associated with reduced insulin sensitivity. This suggests that high, but still normal, fasting glucose may contribute to the augmented insulin secretion in subjects with low insulin sensitivity.

OBJECTIVE—Glucagon-like peptide 1 (GLP-1) is an incretin that augments insulin secretion after meal intake and is developed for treatment of type 2 diabetes. As a novel therapeutic agent, characteristics of its β-cell effects are important to establish. Previously, β-cell effects of GLP-1 have been characterized in humans during graded intravenous infusions of glucose, whereas its effects after more physiological stimuli, like meal intake, are not known. RESEARCH DESIGN AND METHODS—Eight women (aged 69 years, fasting glucose 3.7–10.3 mmol/l, BMI 22.4–43.9 kg/m2) who had fasted overnight were served a breakfast (450 kcal) with intravenous infusion of saline or synthetic GLP-1 (0.75 pmol · kg–1 · min–1), and β-cell function was evaluated by estimating the relationship between glucose concentration and insulin secretion (calculated by deconvolution of C-peptide data). RESULTS—GLP-1 markedly augmented insulin secretion, despite lower glucose. Total insulin secretion was 29.7 ± 4.2 nmol/m2 with GLP-1 versus 21.0 ± 1.6 nmol/m2 with saline (P = 0.048). GLP-1 increased the dose-response relationship between glucose concentration and insulin secretion (70 ± 26 with GLP-1 versus 38 ± 16 pmol insulin · min−1 · m2 · mmol−1 glucose · l without, P = 0.037) and augmented the potentiation factor that modulates the dose response (2.71 ± 0.42 with GLP-1 versus 0.97 ± 0.17 without, P = 0.005). The potentiation factor correlated to GLP-1 concentration (r = 0.53, P < 0.001); a 10-fold increase in GLP-1 levels produced a twofold increase in the potentiation factor. These effects of GLP-1 did not correlate with fasting glucose levels or BMI. CONCLUSIONS—Administration of GLP-1 along with ingestion of a meal augments insulin secretion in humans by a dose-dependent potentiation of the dose-response relationship between plasma glucose and insulin secretion.

OBJECTIVE—To determine the prevalence of type 2 diabetes and impaired fasting glycemia (IFG) in a rural population of Bangladesh. RESEARCH DESIGN AND METHODS—A cluster sampling of 4,923 subjects ≥20 years old in a rural community were investigated. Fasting plasma glucose, blood pressure, height, weight, and girth of waist and hip were measured. BMI and waist-to-hip ratio (WHR) were calculated. Total cholesterol, triglycerides, and HDL cholesterol were also estimated. We used the 1997 American Diabetes Association diagnostic criteria. RESULTS—The crude prevalence of type 2 diabetes was 4.3% and IFG was 12.4%. The age-standardized prevalence of type 2 diabetes (95% CI) was 3.8% (3.12–4.49) and IFG was 13.0% (11.76–14.16). The subjects with higher family income had significantly higher prevalence of type 2 diabetes (5.9 vs. 3.5%, P < 0.001) and IFG (15.6 vs. 10.8%, P < 0.001) than those with lower income. Employing logistic regression in different models, we found that wealthy class, family history of diabetes, reduced physical exercise, and increased age, BMI, and WHR were the important predictors of diabetes. Total cholesterol, triglycerides, and HDL cholesterol showed no association with diabetes and IFG. CONCLUSIONS—The prevalence of diabetes and IFG in the rural population was found to be on the increase compared with the previous reports of Bangladesh and other Asian studies. Older age, higher obesity, higher income, family history of diabetes, and reduced physical activity were proved significant risk factors for diabetes and IFG, whereas plasma lipids showed no association with diabetes and IFG. Further study may address whether diabetes is causally associated with insulin deficiency or insulin resistance.

OBJECTIVE Glucagon-like peptide I(7–36) (GLP-I) amide, an endogenous incretin, has been identified as a potential adjunct to the treatment of NIDDM and has been studied following intravenous and subcutaneous injection. A mucoadhesive buccal GLP-I tablet containing 119 nmol has been developed to provide transmucosal absorption as a possible alternative to injection treatment. RESEARCH DESIGN AND METHODS Eight healthy volunteers received a single tablet under fasting conditions in this randomized double-blind placebo-controlled study. A total GLP-I immunoreactivity was measured using COOH-terminal radioimmunoassay (RIA) (total peptide activity) and NH2-terminal RIA (active, nondegraded peptide). RESULTS The mean (± SE) peak GLP-I concentration was 117 ± 19 pmol/l and occurred 30 ± 4 min after application. The mean placebo-adjusted area under curve was 8,145 ± 873 pmol · min−1 · l−1, consistent with a relative bioavailability of 7% versus intravenous injection and 47% versus subcutaneous injection. The levels of active peptide increased in parallel with total GLP-I. Half-life of peptide activity after buccal administration was 27 and 24 min measured with COOH-terminal and NH2-terminal RIA, respectively. Placebo adjusted insulin concentrations increased to a peak of 252 ± 57 pmol/l, glucose decreased 1.4 ± 0.2 mmo/l, and glucagon decreased 17 ± 3 ng/l, consistent with the increase in plasma GLP-I concentrations. CONCLUSIONS Therapeutic plasma levels of GLP-I in humans were achieved after a single buccal tablet. No increased degradation of GLP-I was found in the buccal mucosa compared to subcutaneous tissue. This alternative treatment form may be feasible in in the future for NIDDM.