Longitudinal changes in insulin sensitivity, insulin secretion, beta cell function and glucose effectiveness during development of non-diabetic hyperglycemia in a Japanese population

High Incidence of Diabetes Mellitus After Distal Pancreatectomy and Its Predictors: A Long-term Follow-up Study

CONTEXT

Glucose tolerance worsens after distal pancreatectomy (DP); however, the long-term incidence and factors affecting interindividual variation in this worsening are unclear.

OBJECTIVE

To investigate the changes in diabetes-related traits before and after DP and to clarify the incidence of diabetes and its predictors.

METHODS

Among 493 registered patients, 117 underwent DP. Among these, 56 patients without diabetes before surgery were included in the study. Glucose and endocrine function were prospectively assessed using a 75-g oral glucose tolerance test preoperatively, 1 month after DP, and every 6 months thereafter for up to 36 months. Pancreatic volumetry was performed using multidetector row computed tomography before and after surgery.

RESULTS

Insulin secretion decreased and blood glucose levels worsened after DP. Residual pancreatic volume was significantly associated with the reserve capacity of insulin secretion but not with blood glucose levels or the development of diabetes. Among 56 patients, 33 developed diabetes mellitus. The cumulative incidence of diabetes at 36 months after DP was 74.1%. Multivariate Cox regression analysis showed that impaired glucose tolerance as a preoperative factor as well as a decreased insulinogenic index and impaired glucose tolerance at 1 month postoperatively were identified as risk factors for diabetes following DP.

CONCLUSION

Impaired glucose tolerance and reduced early-phase insulin response to glucose are involved in the development of new-onset diabetes after DP; the latter is an additional factor in the development of diabetes and becomes apparent when pancreatic beta cell mass is reduced after DP.

The declining insulinogenic index correlates with inflammation and metabolic dysregulation in non-obese individuals assessed by blood gene expression

AIMS

Diabetes onset is difficult to predict. Since decreased insulinogenic index (IGI) is observed in prediabetes, and blood gene expression correlates with insulin secretion, candidate biomarkers can be identified.

METHODS

We collected blood from 96 participants (54 males, 42 females) in 2008 (age: 52.5 years) and 2016 for clinical and gene expression analyses. IGI was derived from values of insulin and glucose at fasting and at 30 min post-OGTT. Two subgroups were identified based on IGI variation: "Minor change in IGI" group with absolute value variation between -0.05 and +0.05, and "Decrease in IGI" group with a variation between -20 and -0.05.

RESULTS

Following the comparison of "Minor change in IGI" and "Decrease in IGI" groups at time 0 (2008), we identified 77 genes correlating with declining IGI, related to response to lipid, carbohydrate, and hormone metabolism, response to stress and DNA metabolic processes. Over the eight years, genes correlating to declining IGI were related to inflammation, metabolic and hormonal dysregulation. Individuals with minor change in IGI, instead, featured homeostatic and regenerative responses.

CONCLUSIONS

By blood gene expression analysis of non-obese individuals, we identified potential gene biomarkers correlating to declining IGI, associated to a pathophysiology of inflammation and metabolic dysregulation.

Three-Year Observation of Glucose Metabolism After Pancreaticoduodenectomy: A Single-Center Prospective Study in Japan

CONTEXT

The glucose tolerance of patients changes considerably from before to after pancreaticoduodenectomy wherein approximately half of the pancreas is resected.

OBJECTIVE

The aim of this prospective study was to investigate the incidence of and risk factors for diabetes after pancreaticoduodenectomy.

METHODS

This study is a part of an ongoing prospective study, the Kindai Prospective Study on Metabolism and Endocrinology after Pancreatectomy (KIP-MEP) study. Of the 457 patients enrolled to date, 96 patients without diabetes who underwent pancreaticoduodenectomy were investigated in this study. Preoperatively, 1 month post-pancreaticoduodenectomy, and every 6 months thereafter, the glucose metabolism and endocrine function were evaluated using the 75 g oral glucose tolerance test. Various other metabolic, endocrine, and exocrine indices were also examined over a period of up to 36 months.

RESULTS

Of the 96 patients analyzed in this study, 33 were newly diagnosed with diabetes. The cumulative diabetes incidence at 36 months following pancreaticoduodenectomy was 53.8%. The preoperative insulinogenic index and ΔC-peptide in the glucagon stimulation test were significantly lower in the progressors to diabetes than in the nonprogressors. Multivariate Cox regression analysis demonstrated that the insulinogenic index was the only significant risk factor for new-onset diabetes.

CONCLUSION

The majority of patients developed new-onset diabetes after pancreaticoduodenectomy, and a low value of the insulinogenic index was suggested to be a risk factor for diabetes. Preoperative assessment for the prediction of the onset of diabetes serves as useful information for patients and is important for postoperative glycemic control and diabetes management in patients who require pancreaticoduodenectomy.

Insulin and Proinsulin Dynamics Progressively Deteriorate From Within the Normal Range Toward Impaired Glucose Tolerance

Context

Slight elevations in plasma glucose (PG) manifest in advance of diabetes onset, but abnormalities in immunoreactive insulin (IRI), proinsulin (Pro), and adiponectin dynamics during this stage remain poorly understood.

Objective

The objective of this work is to investigate whether IRI and Pro dynamics become abnormal as glucose tolerance deteriorates from within the normal range toward impaired glucose tolerance (IGT), as well as the relationship between PG, and these dynamics and serum adiponectin levels.

Design

A cross-sectional study was designed.

Setting

This study took place at Jichi Medical University in Japan.

Participants and Measurements

PG, IRI, and Pro levels were determined in 1311 young Japanese individuals (age < 40 years) with normal or IGT before and at 30, 60, and 120 minutes during a 75-g oral glucose tolerance test. Participants were assigned to 4 groups according to glucose tolerance, and then background factors, adiponectin levels, insulin sensitivity (SI), and insulin secretion (β) indexes were determined.

Results

PG levels as well as IRI and Pro levels 60 and 120 minutes after glucose-loading increased incrementally with deteriorating glucose tolerance. All measures of β and the SI measure index of insulin sensitivity (ISI)-Matsuda decreased incrementally. Serum adiponectin levels were not significantly different among the glucose tolerance groups, but were independently and negatively correlated with fasting glucose.

Conclusions

Early β decreased and postloading Pro levels became excessive in a progressive manner as glucose tolerance deteriorated from within the normal range toward IGT.

Contribution of Oxidative Stress and Impaired Biogenesis of Pancreatic β-Cells to Type 2 Diabetes

Significance: Type 2 diabetes development involves multiple changes in β-cells, related to the oxidative stress and impaired redox signaling, beginning frequently by sustained overfeeding due to the resulting lipotoxicity and glucotoxicity. Uncovering relationships among the dysregulated metabolism, impaired β-cell "well-being," biogenesis, or cross talk with peripheral insulin resistance is required for elucidation of type 2 diabetes etiology. Recent Advances: It has been recognized that the oxidative stress, lipotoxicity, and glucotoxicity cannot be separated from numerous other cell pathology events, such as the attempted compensation of β-cell for the increased insulin demand and dynamics of β-cell biogenesis and its "reversal" at dedifferentiation, that is, from the concomitantly decreasing islet β-cell mass (also due to transdifferentiation) and low-grade islet or systemic inflammation. Critical Issues: At prediabetes, the compensation responses of β-cells, attempting to delay the pathology progression-when exaggerated-set a new state, in which a self-checking redox signaling related to the expression of Ins gene expression is impaired. The resulting altered redox signaling, diminished insulin secretion responses to various secretagogues including glucose, may lead to excretion of cytokines or chemokines by β-cells or excretion of endosomes. They could substantiate putative stress signals to the periphery. Subsequent changes and lasting glucolipotoxicity promote islet inflammatory responses and further pathology spiral. Future Directions: Should bring an understanding of the β-cell self-checking and related redox signaling, including the putative stress signal to periphery. Strategies to cure or prevent type 2 diabetes could be based on the substitution of the "wrong" signal by the "correct" self-checking signal.

Type 2 Diabetes: When Does It Start?

Objective

We aimed to clarify the onset of diabetes.

Design

Data from 27,392 nondiabetic health examinees were retrospectively analyzed for a mean of 5.3 years. Trajectories of fasting plasma glucose (FPG), body mass index (BMI), and the single point insulin sensitivity (Si) estimator (SPISE), an index of Si, 10 years before diagnosis of prediabetes (PDM; n = 4781) or diabetes (n = 1061) were separately assessed by a mixed effects model. Diabetes and PDM were diagnosed by the American Diabetes Association definition on the basis of FPG and glycosylated hemoglobin A1c values.

Results

In individuals who developed diabetes, mean FPG and BMI were significantly higher (P < 0.01 each) and SPISE lower than those who did not at -10 years: FPG 101.5 mg/dL vs 94.5 mg/dL, BMI 24.0 kg/m² vs 22.7 kg/m², and SPISE 7.32 vs 8.34, P < 0.01 each. These measurements, in subjects who developed prediabetes, were slightly but definitely different from those who did not, already at -10 years: FPG 91.8 mg/dL vs 89.6 mg/dL, BMI 22.6 kg/m² vs 22.1 kg/m², and SPISE 8.44 vs 8.82, P < 0.01 each. In both cases, the differences were progressively greater toward year 0, the time of diabetes, or PDM diagnosis.

Conclusions

FPG was significantly elevated in those who developed diabetes at least 10 years before diagnosis of diabetes, and this was also the case in those who developed PDM. Glucose dysregulation precedes diagnosis of diabetes at least for 20 years.

Residual β-Cell Function Predicts Clinical Response After Autologous Hematopoietic Stem Cell Transplantation

New strategies of autologous hematopoietic stem cell transplantation (auto-HSCT) have gained much interest for the treatment of type 1 diabetes mellitus. However, assessing the clinical response and residual β-cell function still has limitations. The aim of the study was to select the optimal quantitative index to assess pre-existing β-cell function and to explore its predictive function for clinical response after auto-HSCT therapy. In this study, all of the patients who had undergone auto-HSCT were clustered into a responder group (Δβ-score > 0) and a nonresponder group (Δβ-score ≤ 0). We compared their quantitative metabolic indexes at baseline and performed receiver-operating characteristic (ROC) analysis to analyze the correlations between the indexes and clinical response. Kaplan-Meier analysis was conducted to compare the cumulative response durations in each quartile of the selected indexes. In an average of 15.13 ± 6.15 months of follow-up, 44 of 112 patients achieved a clinical response. The responder group had lower levels of fasting plasma glucose and quantitative insulin sensitivity check index (QUICKI) but higher levels of fasting C-peptide, fasting insulin, and homeostasis model assessments for insulin resistance (HOMA-IR). ROC analysis showed that HOMA-IR had the largest area under the curve (0.756), which was similar to that of QUICKI. Kaplan-Meier analysis further confirmed that the third quartile (1.3371-1.7018) of HOMA-IR or the second quartile (0.3523-0.3657) of QUICKI was preferential for a prolonged response. In conclusion, HOMA-IR and QUICKI could be optimal measurements for β-cell reserves, and they were predictive for the clinical response after auto-HSCT.

SIGNIFICANCE

The β-score was comprehensive and reliable in evaluating clinical response after autologous hematopoietic stem cell transplantation (HSCT). The homeostasis model assessments for insulin resistance and the quantitative insulin sensitivity check index could serve as precise assessments for residual β-cell function and good predictors of clinical response. They might be used to select optimal clinical trial participants or predict the clinical response after auto-HSCT.

Impact of one-hour postchallenge glucose on the relationship between insulin sensitivity and secretion

The impact of postchallenge glucose on the relationship between insulin sensitivity (SI) and secretion (β) is unknown. We analyzed data from 2,264 health examinees (male/female 1,524/740, median age 54 yrs) with normal glucose tolerance (NGT, n = 1,623), non-diabetic hyperglycemia (NDH, n = 555), or diabetes (DM, n = 86) using OGTT-derived indices of SI (insulin sensitivity index [ISI]-Matsuda, 1/HOMA-IR, and 1/fasting IRI) and β (δIRI0-30/δPG0-30, and Stumvoll 1st [Stumvoll-1] and 2nd [Stumvoll-2] phases). The combination of 1/HOMA-IR and Stumvoll-1 recapitulated the hyperbolic SI-β relationship with the slope of the fitted line -1.000 in NGT subjects, and therefore it was utilized in the following analysis of the SI-β correlation. In multiple regression analysis of the relationship between SI and β, an independent correlation was found for 1 h-plasma glucose (PG; PG60) but not for 2 h-PG. When the NGT subjects were grouped by PG60 quartile (Q), the fitted line was flat in Q1 but progressively steeper from Q2 to Q4, with a slope (95%CI) of -0.663 (-0.726~-0.605), -0.680 (-0.745~-0.622), -0.847 (-0.922~-0.779), and -1.259 (-1.370~-1.158) (P for trend < 0.05). The fitted line steepened further in the NDH and DM groups, with a slope of -1.545 and -1.915, respectively (P < 0.01 for the difference). The intercept of the fitted line for SI-β correlation was also progressively lower across the PG60 Q for NGT, NDH, and DM. In conclusion, using the 1/HOMA-IR-Stumvoll-1 pair for an analysis of the SI-β relationship, elevated PG60 was associated with steepening and downward shifting of the fitted line for the SI-β correlation. The finding suggests impaired beta cell function.