Diagnostic Accuracy of an “Amended” Insulin–Glucose Ratio for the Biochemical Diagnosis of Insulinomas

Nauck MA, Meier JJ. — Tue, 04 Dec 2012 00:00:00 GMT

Background:

Recent biochemical diagnostic guidelines for insulinomas require demonstration of hypoglycemia with inappropriately elevated (nonsuppressed) insulin, C-peptide, or proinsulin, but these criteria may overlap with those in patients without insulinomas. Use of an “amended” insulin–glucose ratio that accounts for the normal variation in insulin secretion according to prevailing glycemia may improve diagnostic accuracy.

Objective:

To compare the diagnostic accuracy of current diagnostic guideline criteria with the amended insulin–glucose ratio in patients with a suspected insulinoma.

Design:

Retrospective cohort study.

Setting:

2 specialized university departments in Germany.

Patients:

114 patients with suspected hypoglycemia over 10 years having diagnostic prolonged fasts.

Measurements:

Glucose, insulin, C-peptide, and the amended insulin–glucose ratio were measured during and at discontinuation of prolonged fasts.

Results:

Of 114 patients who were evaluated, 49 had surgical resection of histologically confirmed insulinomas. Insulinoma was excluded in 65 patients; follow-up for a mean of 10 years (range, 0 to 16 years) showed no progressively severe hypoglycemic events or diagnoses of insulinoma. Patients with insulinoma had lower glucose levels and higher insulin and C-peptide levels overall than did control patients at the end of prolonged fasts, but there was considerable overlap. The amended insulin–glucose ratio correctly identified 48 of 49 patients with insulinoma and excluded the diagnosis in 64 of 65 control patients, resulting in positive and negative predictive values of 0.98 (95% CI, 0.89 to 1.00) and 0.99 (CI, 0.92 to 1.00), respectively, compared with 0.75 (CI, 0.63 to 0.85) and 0.98 (CI, 0.89 to 1.00), respectively, for glucose, insulin, and C-peptide concentration criteria.

Limitation:

The study had a retrospective design, no proinsulin concentrations were available, and a nonspecific insulin immunoassay (crossreactive with proinsulin) was used.

Conclusion:

The amended insulin–glucose ratio showed improved diagnostic accuracy over established criteria that use glucose, insulin, and C-peptide concentrations.

Primary Funding Source:

None.

Review: Statins reduce pancreatitis in adults with normal or mildly elevated triglyceride levels

Bloomfield HE. — Tue, 18 Dec 2012 00:00:00 GMT

Question

Do statins or fibrates affect risk for pancreatitis in adults?

Review scope

Included studies evaluated the effect of statin or fibrate therapy on cardiovascular events, randomized ≥ 1000 adults, and had a mean follow-up of ≥ 1 year. Exclusion criteria included trials of patients who had previous organ transplantation or were receiving hemodialysis, or trials comparing combination therapy with placebo. Outcome was pancreatitis.

Review methods

MEDLINE, EMBASE/Excerpta Medica, and Web of Science were searched for randomized controlled trials (RCTs) published between 1972 (fibrate trials) or 1994 (statin trials) and 9 June 2012. Reference lists of identified studies and the US Food and Drug Administration Web site were also searched. 21 RCTs of statins (n = 153 414, mean or median age 55 to 75 y, mean triglyceride level 118 to 187 mg/dL [1.33 to 2.11 mmol/L], weighted mean follow-up 4.3 y, median Jadad score 5 out of 5) and 7 RCTs of fibrates (n = 40 162, mean age 46 to 64 y, mean triglyceride level 145 to 184 mg/dL [1.64 to 2.08 mmol/L], weighted mean follow-up 5.3 y, all had Jadad scores of 5) met the selection criteria. Pancreatitis data were unpublished in 22 of the 28 studies.

Main results

Meta-analysis showed that statins reduced risk for pancreatitis compared with control (Table). Risk for pancreatitis did not differ between intensive- and moderate-dose statins or between fibrate and control (Table).

Conclusions

Statins reduce risk for pancreatitis in adults. Fibrates do not affect risk for pancreatitis.Statins or fibrates vs control and risk for pancreatitis in adults*Comparison (follow-up)Number of trials (n)Weighted event ratesRRR (95% CI)NNT (CI) over 5 yStatins vs control (mean 4 y)16 (113 800)0.2% vs 0.3%23% (3 to 38)1175 (693 to 9195)Intensive- vs moderate-dose statins (mean 5 y)5 (39 614)0.35% vs 0.43%18% (−12 to 41)Not significantRRI (CI)NNH (CI)Fibrates vs control (mean 5 y)7 (40 162)0.4% vs 0.3%39% (0 to 95)Not significant*Abbreviations defined in Glossary. RRR, RRI, and CI calculated from control event rates and risk ratios in article using a random-effects model.

Annals of Internal Medicine: Pancreatic Disease Topic Collection

Diagnostic Accuracy of an “Amended” Insulin–Glucose Ratio for the Biochemical Diagnosis of Insulinomas

Review: Statins reduce pancreatitis in adults with normal or mildly elevated triglyceride levels