Rizza, Robert A.

Abstract The sections in this article are: Pathogenesis of Type I Diabetes Effect of Type I Diabetes on Carbohydrate Metabolism Insulin Secretion and Action Postabsorptive and Postprandial Carbohydrate Metabolism Effects of Type I Diabetes and Its Treatment on Fatty Acid Metabolism Adipose Tissue Postabsorptive FFA Metabolism Postprandial FFA Availability Effects of Exercise on Adipose Tissue Lipolysis Regulation of Lipolysis During Hypoglycemia Effects Of Type I Diabetes on Protein Metabolism Regulation of Body Protein Mass, Amino Acid Levels and Nitrogen Balance Effect of Insulin on Protein Balance and Interaction of Insulin with Other Hormones and Substrates Effects of Insulin on Whole‐Body Protein Dynamics Effect of Insulin on Amino Acid Transamination Effect of Insulin on Regional Protein Dynamics Effect of Insulin on the Synthesis Rates of Specific Proteins Impact of Type I Diabetes on Protein Metabolism

ABSTRACT Importance Despite the current enthusiasm for anti‐obesity medications, there is a critical need for effective lifestyle interventions that can be broadly implemented. Objective To assess the effectiveness of REWIND, an obesity and diabetes treatment program. Design Prospective cohort study. Setting Virtual, community‐based weight management program. Participants Two‐hundred and nineteen participants, BMI ≥ 30 kg/m 2 , with and without type 2 diabetes (T2D). Intervention Three phases: “induction” with meal replacement diet to promote ≥ 15% weight loss; “transition” to everyday foods; and “maintenance” to prevent weight regain. REWIND leveraged teams including community leaders, media personalities, nationally recognized athletes and participants, to disseminate information, and foster belonging, commitment, and resilience. Main Outcomes The co‐primary outcomes were the change in weight at 6‐, 12‐, and 18 months. Secondary outcomes were the proportion of patients achieving ≥ 5%, 10%, 15%, and 20% weight loss at 6, 12, and 18 months, and remission rates in T2D at 6‐, 12‐, and 18‐month, respectively. Results Two hundred and nineteen participants (mean age 49.1 [SD 10.5] years), 37% men, 12% Black, 26% with T2D. Weight decreased from: 114.4 (20.8) kg to 96.1 (18.4) kg at 6 months, to 98.5 (18.1) kg at 12 months, and to 101.1 (20.5) kg at 18 months. Weight loss percentages at 6, 12, and 18 months were ≥ 5%: 95%, 91%, 84%; ≥ 10%: 79%, 72%, 67%; ≥ 15%: 58%, 46%, 47%; and ≥ 20%: 24%, 25%, 22%. Diabetes remission was achieved by 52% and 43% of participants with T2D at 12‐ and 18‐month, respectively. Limitations Single geographic region. Weight was self‐reported. Conclusion A virtual community‐based program for individuals with obesity and T2D facilitated substantial weight loss and T2D remission. This model has the potential for wide‐scale implementation in diverse settings.

Glucose production is inappropriately increased in people with type 2 diabetes both before and after food ingestion. Excessive postprandial glucose production occurs in the presence of decreased and delayed insulin secretion and lack of suppression of glucagon release. These abnormalities in hormone secretion, coupled with impaired insulin-induced suppression of glucose production and stimulation of splanchnic glucose uptake, likely account in large part for the excessive amounts of glucose that reach the systemic circulation for disposal by peripheral tissues following food ingestion. In contrast, when adequate basal insulin concentrations are present, neither glucagon-induced stimulation of glucose production nor glucose-induced suppression of glucose production differs in diabetic and nondiabetic subjects matched for gender, age, and degree of obesity. However, when insulin secretion is defective, lack of suppression of glucagon can cause substantial hyperglycemia by enhancing rates of glucose production. Therefore, normalization of hepatic glucose metabolism in people with type 2 diabetes mellitus likely will require normalization of insulin and glucagon secretion as well as hepatic insulin action.

Abstract Objective Pulsatile insulin secretion is impaired in diseases such as type 2 diabetes that are characterized by insulin resistance. This has led to the suggestion that changes in insulin pulsatility directly impair insulin signaling. We sought to examine the effects of pulse characteristics on insulin action in humans, hypothesizing that a decrease in pulse amplitude or frequency is associated with impaired hepatic insulin action. Methods We studied 29 nondiabetic subjects on two occasions. On 1 occasion, hepatic and peripheral insulin action was measured using a euglycemic clamp. The deuterated water method was used to estimate the contribution of gluconeogenesis to endogenous glucose production. On a separate study day, we utilized nonparametric stochastic deconvolution of frequently sampled peripheral C-peptide concentrations during fasting to reconstruct portal insulin secretion. In addition to measuring basal and pulsatile insulin secretion, we used approximate entropy to measure orderliness and Fourier transform to measure the average, and the dispersion of, insulin pulse frequencies. Results In univariate analysis, basal insulin secretion (R2 = 0.16) and insulin pulse amplitude (R2 = 0.09) correlated weakly with insulin-induced suppression of gluconeogenesis. However, after adjustment for age, sex, and weight, these associations were no longer significant. The other pulse characteristics also did not correlate with the ability of insulin to suppress endogenous glucose production (and gluconeogenesis) or to stimulate glucose disappearance. Conclusions Overall, our data demonstrate that insulin pulse characteristics, considered independently of other factors, do not correlate with measures of hepatic and peripheral insulin sensitivity in nondiabetic humans.

AbstractIntroductionWe sought to determine whether chromogranin A‐positive hormone‐negative (CPHN) endocrine cells are increased in the pancreas of pregnant women, offering potential evidence in support of neogenesis.MethodsAutopsy pancreata from pregnant women (n = 14) and age‐matched non‐pregnant control women (n = 9) were obtained. Staining of pancreatic sections for chromogranin A, insulin and a cocktail of glucagon, somatostatin, pancreatic polypeptide and ghrelin was undertaken, with subsequent evaluation for CPHN cell frequency.ResultsThe frequency of clustered β‐cells was increased in pregnant compared to non‐pregnant subjects (46.6 ± 5.0 vs. 31.8 ± 5.0% clustered β‐cells of total clustered endocrine cells, pregnant vs. non‐pregnant, p < .05). Frequency of endocrine cocktail cells was lower in pregnant women than non‐pregnant women (36.2 ± 4.0 vs. 57.0 ± 6.8% clustered endocrine cocktail cells of total clustered endocrine cells, pregnant vs. non‐pregnant, p < .01). No difference in frequency of CPHN cells was found in islets, nor in clustered or single cells scattered throughout the exocrine pancreas, between pregnant and non‐pregnant women. The frequency of CPHN cells in pregnancy was independent of the number of pregnancies (gravidity).ConclusionsOur findings of no increase in CPHN cell frequency in pancreas of pregnant women suggest that this potential β‐cell regenerative mechanism is not that by which the increased β‐cell mass of pregnancy is achieved. However, an increase in the percentage of clustered β‐cells was found in pregnancy, with decreased frequency of other endocrine cells in clusters, suggesting a compensatory shift from other pancreatic endocrine cell types to β‐cells as a mechanism to meet the increased insulin demands of pregnancy.

BACKGROUND Metabolic disorders such as type 2 diabetes have been associated with a decrease in insulin pulse frequency and amplitude. We hypothesized that the T allele at rs7903146 in TCF7L2, previously associated with β cell dysfunction, would be associated with changes in these insulin pulse characteristics. METHODS Twenty-nine nondiabetic subjects (age 46 ± 2, BMI 28 ± 1 kg/m 2 ) participated in this study. Of these, 16 were homozygous for the C allele at rs7903146 and 13 were homozygous for the T allele. Deconvolution of peripheral C-peptide concentrations allowed the reconstruction of portal insulin secretion over time. These data were used for subsequent analyses. Pulse orderliness was assessed by approximate entropy (ApEn), and the dispersion of insulin pulses was measured by a frequency dispersion index (FDI) after a Fast Fourier Transform (FFT) of individual insulin secretion rates. RESULTS During fasting conditions, the CC genotype group exhibited decreased pulse disorderliness compared with the TT genotype group (1.10 ± 0.03 vs. 1.19 ± 0.04, P = 0.03). FDI decreased in response to hyperglycemia in the CC genotype group, perhaps reflecting less entrainment of insulin secretion during fasting. CONCLUSION Diabetes-associated variation in TCF7L2 is associated with decreased orderliness and pulse dispersion, unchanged by hyperglycemia. Quantification of ApEn and FDI could represent novel markers of β cell health. FUNDING This work was funded by US NIH (DK78646, DK116231), University of Padova research grant CPDA145405, and Mayo Clinic General Clinical Research Center (UL1 TR000135).

Aim To establish pancreatic alpha-cell mass in lean, non-diabetic humans over the adult lifespan, performed as a follow-up study to beta-cell mass across the adult human lifespan. Methods We examined human pancreatic autopsy tissue from 66 lean, non-diabetic individuals aged from 30 to 102 years, grouped into deciles: 3rd (30–39 years), 4th (40–49 years), 5th (50–59 years), 6th (60–69 years), 7th (70–79 years), 8th (80–89 years) and 9th deciles (90+ years). Sections of pancreas were immunostained for glucagon and analyzed for fractional alpha-cell area. Population-based pancreatic volume data were used to calculate alpha-cell mass. Results With advanced age, the exocrine pancreas undergoes atrophy demonstrated by increased fat area (as % exocrine area) (0.05 ± 0.01 vs 1.6 ± 0.7% fat area of total exocrine pancreas, 3rd vs 9th decile, P < 0.05). Consequently, islet density increases with age (2.7 ± 0.4 vs 10.5 ± 3.3 islets/mm2, 3rd vs 9th decile, P < 0.05). Alpha-cell fractional area increases with advanced age (0.34 ± 0.05% vs 0.73 ± 0.26%, 3rd vs 9th decile, P < 0.05). However, alpha-cell mass remains constant at ~190 mg throughout the adult lifespan in lean, non-diabetic humans. Within islets, alpha-cell distribution between mantle and core is unchanged across deciles (1862 ± 220 vs 1945 ± 200 vs 1948 ± 139 alpha cells in islet mantle/mm2, 3rd vs 6th vs 9th decile, P = 0.93 and 1912 ± 442 vs 1449 ± 123 vs 1514 ± 168 alpha cells in islet core/mm2, 3rd vs 6th vs 9th decile, P = 0.47), suggesting that human islets retain their structural organization in the setting of age-related exocrine atrophy. Conclusions Consistent with our previous findings for beta-cell mass, alpha-cell mass remains constant in humans, even with advanced age. Pancreatic endocrine cells are much more robustly preserved than exocrine cells in aged humans, and islets maintain their structural integrity throughout life.

Abstract Abstract 4908 Insulin resistance can be a major problem in patients with diabetes mellitus. Although multiple reasons can result in this problem, one of the rare causes is localized insulin induced cutaneous amyloidosis. Lack of recognition of this may result in fatal hypoglycemia if a higher dose of insulin is given at a different site. A 43-year-old female diagnosed with diabetes mellitus in 1986 after acute pancreatitis secondary to hypertriglyceridemia presented to our hospital in December of 2008 with a 2 year history of low grade fever of 99-100F. This was associated with chills and fatigue. Over the same time period she had noticed anterior abdominal wall nodularity, particularly at sites where she has been injecting her insulin. Her insulin requirement had also increased from a total of 60 units of NPH in a day to 170 units per day. Because of the subcutaneous nodularity at the site of injection a decision was made to switch the site of the insulin which resulted in lower blood glucose level and subsequently significant decrease in her insulin requirement to 120 units a day. This suggested poor absorption from the infiltrated site. At our clinic laboratory data showed normal white count of 5.4 × 10(9)/L with normal differential, normal hemoglobin of 12.9 g/dL with an ESR of 11 mm/hour, creatinine of 0.8 mg/dL and C-reactive protein of less than 3. As part of the work up for fever of unknown origin a CT-scan of the abdomen was obtained which showed infiltrative lesion in the anterior abdominal subcutaneous tissue with few calcifications Fig 1 & 2. Biopsy of the anterior abdominal wall nodular infiltrate was performed. Tissue cultures came out negative for infection. The biopsy showed eosinophilic material positive with Congo red staining and showing apple green birefringence when viewed under polarized light. Immunohistochemical staining showed this to be negative for AA, AL, or TTR amyloidosis. Liquid chromatography tandem mass spectrometry (LC MS/MS) detected peptides representing apolipoprotein E, apolipoprotein A-IV, SAP and Insulin. The amyloid deposits stained positive with anti-insulin. The presence of peptides from insulin and immunohistochemical reactivity with an anti-insulin antibody indicated that the amyloid deposits were caused by insulin injection at this site. Work up for systemic amyloidosis including serum protein electrophoresis with immunofixation was negative for a monoclonal protein. Quantitative immunoglobulins were within normal range. Her 24-hour urine protein was 65 mg within normal range. Her serum free light chains were unremarkable. Echocardiogram did not show any evidence of infiltrative cardiomyopathy. This was therefore consistent with localized insulin induced cutaneous amyloidosis. The recommendation was to change the insulin type and to rotate the insulin injection site. Because of occasional hemorrhage and pain the long term plan will be to surgically remove the amyloid deposits. Insulin mediated iatrogenic localized amyloidosis has been described previously in the literature at the sites of insulin injection in patients with diabetes. This is a rare complication of insulin therapy and must be considered in the differential diagnosis of patients with insulin resistance to prevent fatal hypoglycemia. Fig 1. Amyloid infiltration in subcutaneous tissue of upper abdomen at insulin injection site Fig 1. Amyloid infiltration in subcutaneous tissue of upper abdomen at insulin injection site Fig 2. Amyloid infiltration in subcutaneous tissue of lower abdomen at insulin injection site Fig 2. Amyloid infiltration in subcutaneous tissue of lower abdomen at insulin injection site Disclosures No relevant conflicts of interest to declare.