Visceral fat deposition is seen in patients with insulinoma

Non-surgical ablative therapies for inoperable benign insulinoma

PURPOSE

Benign insulinoma is the most common functioning neuroendocrine tumor of the pancreas. The gold-standard therapeutic approach for insulinoma is surgery, which allows for tumor removal, histology and immunochemical analyses. If surgery is not feasible, minimally invasive ablative procedures performed by interventional radiology can lead to partial or complete remission of hormone hypersecretion and tumor control in insulinoma patients.

METHODS

We performed a review of existing literature on non-chemotherapeutic/radioactive ablative techniques employed for the treatment of benign, otherwise inoperable, pancreatic insulinoma. For this purpose, feasibility, effectiveness and safety of ablative treatments for pancreatic insulinoma were reviewed from literature data published from 1982 to date.

RESULTS

A total of 44 insulinoma cases treated with non-surgical ablative techniques were desumed, and divided as follows: 7 cases of tumor embolization, 26 ethanol ablations, 7 radiofrequency ablations, 2 high intensity focused ultrasound ablation, 1 irreversible electroporation and 1 percutaneous microwave ablation. Most cases involved single insulinoma, predominantly located in the pancreas head and body. In the majority of patients, ablation was chosen instead of surgery due to severe comorbidities. After an average follow-up of 16 months, the overall success rate of non-surgical ablative treatments of insulinoma was 84%, the recurrence/persistence rate was 16%, and transient adverse events were noted in 23% of cases. Adverse events were usually self-limiting and medically manageable.

CONCLUSIONS

Non-surgical ablation is a feasible, safe and repeatable procedure in patients with pancreatic insulinoma, who are not candidate to surgery or refuse it. Partial or complete control of symptoms and tumor growth is experienced by the majority of patients.

Effects of bed-time insulin versus pioglitazone on abdominal fat accumulation, inflammation and gene expression in adipose tissue in patients with type 2 diabetes

AIMS/HYPOTHESIS

Intra-abdominal fat (IAF) and inflammatory markers are correlated with cardio-vascular risk. We compared the impact of bed-time insulin versus pioglitazone treatment on these parameters in type 2 diabetic (T2D) patients.

METHODS

Twenty-eight T2D patients poorly controlled with metformin and sulfonylurea were randomized to receive add-on therapy with pioglitazone or bed-time NPH insulin. IAF and subcutaneous fat (SCF) content, systemic low-grade inflammation level and expression of inflammation related genes in SCF, were measured before and after 24 weeks of treatment.

RESULTS

Insulin and pioglitazone resulted in a significant decrease in HbA1c (-1.6% and -1.2%, respectively) and a significant increase in total body fat mass (1+/-2.3 and 3.3+/-2.7 kg, respectively). There was no change in IAF content after both treatments whereas significant increase in SCF content was only seen after pioglitazone treatment (p<0.05 versus insulin). hsCRP level decreased after pioglitazone and ferritin level decreased after insulin treatment. No change in mRNA expression of inflammation related genes was found after either treatment.

CONCLUSION/INTERPRETATION

This suggests that a 24-week treatment with pioglitazone or bed-time insulin has a similar impact on intra-abdominal fat mass and systemic low-grade inflammation.

Lipoprotein lipase mass and activity in post-heparin plasma from subjects with intra-abdominal visceral fat accumulation

OBJECTIVES

The purpose of this study was to investigate the possibility of impaired lipolysis of triglyceride-rich lipoproteins in patients with abdominal visceral fat accumulation by assessing two major lipolytic enzymes in the plasma, lipoprotein lipase (LPL) and hepatic lipase (HL).

DESIGN AND PATIENTS

A total of 31 patients [20 men, 11 women, age 50 +/- 7 years old, body mass index (BMI) 26 +/- 2 kg/m2 (mean +/- sd)] were analyzed. Visceral fat and subcutaneous fat areas were evaluated using a computerized tomographic (CT) method at the level of the umbilicus. Total lipolytic activity in the postheparin plasma (PHP) was measured using Triton X-100-emulsified triolein and LPL activity was calculated as the activity in whole plasma inhibited by the 5D2 monoclonal antibody for LPL. LPL enzyme mass was determined by a sandwich enzyme immunoassay.

RESULTS

The visceral fat area was found to be negatively correlated with LPL mass (V vs LPL mass, r = -0.37, P = 0.04) in PHP and had a tendency toward negative correlation with the LPL activity in the PHP (V vs LPL activity, r = -0.29, P = 0.12). Subcutaneous fat area, on the other hand, did not show any correlation with LPL activity (r = 0.13, P = 0.49) or mass (r = 0.22, P = 0.25) in the PHP. The visceral fat area was found to be positively correlated with fasting serum insulin levels (r = 0.67, P < 0.01). Body mass index (BMI) was not correlated with LPL mass or activity in the PHP. Multi-regressional analysis showed that abdominal visceral fat could be correlated with LPL mass in the PHP, independently of fasting serum insulin. The HL activity from PHP of the patients did not show significant correlation with visceral fat area, subcutaneous fat area or body mass index.

CONCLUSIONS

Fat distribution affects LPL mass and activity, either directly or via another metabolic abnormality such as insulin resistance, leading to impaired hydrolysis of triglycerides in chylomicrons and very low density lipoproteins (VLDL) in these subjects.

Disordered metabolism in diabetes: have we underemphasized the fat component?

Despite intensive investigation, a clear understanding of the metabolic disturbances in diabetes mellitus and their temporal relationship to each other during disease development has still not emerged. With emphasis on non-insulin-dependent diabetes (NIDDM), three possibilities are explored here: (1) that the insulin resistance characteristic of obesity/NIDDM syndromes is the result rather than the cause of hyperinsulinemia, as is widely held, (2) that the linkage between hyperactivity of the pancreatic beta-cell and peripheral insulin resistance is vested in excessive delivery of lipid substrate from liver to the muscle bed, and (3) the conceivably hyperamylinemia works in concert with hyperinsulinemia in promoting overproduction of very-low-density lipoproteins by the liver, and thus in the etiology of muscle insulin resistance.