Administration of Neutral Protamine Hagedorn Insulin at Bedtime versus with Dinner in Type 1 Diabetes Mellitus To Avoid Nocturnal Hypoglycemia and Improve Control

A Randomized, Controlled Trial

2 April 2002 | Volume 136 Issue 7 | Pages 504-514

Background: Intensive insulin treatment of type 1 diabetes mellitus increases the risk for nocturnal hypoglycemia.

Objective: To demonstrate that splitting the evening insulin regimen reduces the risk for nocturnal hypoglycemia in intensive treatment of type 1 diabetes mellitus.

Design: Randomized, open, two-treatment crossover trial in two 4-month periods.

Setting: University research center in Italy.

Patients: 22 C-peptide–negative persons with type 1 diabetes mellitus (mean age [±SD], 29 ± 3 years).

Interventions: Each patient was randomly assigned to one of two insulin regimens for 4 months and then switched to the other regimen for another 4 months. The two treatment regimens were 1) mixed treatment—a mixture of human regular and neutral protamine Hagedorn [NPH] insulin administered before dinner and 2) split treatment—human regular insulin administered at dinner and NPH insulin administered at bedtime.

Measurements: Frequency of nocturnal hypoglycemia. Secondary end points were levels of fasting blood glucose and hemoglobin A_1c and responses to experimental hypoglycemia.

Results: During the split-regimen treatment period, patients had fewer episodes of nocturnal hypoglycemia (mean [±SE], 0.10 ± 0.02 episode/patient-day vs. 0.28 ± 0.04 episode/patient-day; P = 0.002), a lower fasting blood glucose level (mean [±SE], 7.6 ± 0.2 mmol/L vs. 8.3 ± 0.5 mmol/L [137 ± 4 mg/dL vs. 160 ± 8 mg/dL]; P = 0.030), less variable fasting blood glucose levels (SD range, 2.0 ± 0.4 vs. 3.5 ± 0.6; P = 0.001), and lower hemoglobin A_1c value (mean [±SE], 7.0% ± 0.11% vs. 7.5% ± 0.15%; P = 0.004) than during the mixed regimen. Responses to experimental hypoglycemia were better preserved with the split regimen than with the mixed regimen.

Conclusion: When the goal of insulin therapy in type 1 diabetes mellitus is near-normoglycemia, splitting the evening insulin treatment regimen into short-acting insulin at dinner and NPH insulin at bedtime reduces the risks for nocturnal hypoglycemia and hypoglycemia unawareness and decreases the hemoglobin A_1c value compared with mixing short-acting insulin and NPH insulin at dinner.

Editors' Notes Context Clinicians often split evening insulin dosing (short-acting insulin at dinner and long-acting insulin at bedtime rather than both types with dinner) to avoid nocturnal hypoglycemia in patients with type 1 diabetes mellitus. Although split dosing makes sense theoretically, no rigorous studies have examined its effects on glycemic control. Contribution In this randomized, controlled crossover trial, episodes of nocturnal hypoglycemia were less frequent and fasting blood glucose and hemoglobin A1c levels were lower with split evening insulin than with mixed dosing at dinner. Clinical Implications This study supports splitting evening insulin dosing to improve glycemic control in patients with intensively treated type 1 diabetes. –The Editors

 

Author and Article Information

From University of Perugia, Perugia, Italy.

Acknowledgments: The authors thank Mad Judge Stout in Falkland Arms, Great Tew, United Kingdom, for his support.

Grant Support: By Juvenile Diabetes Research Foundation International (grant 1-2001-102).

Requests for Single Reprints: Geremia B. Bolli, MD, Department of Internal Medicine, University of Perugia, Via E. Dal Pozzo, I-06126 Perugia, Italy; e-mail, gbolli{at}dimisem.med.unipg.it.

Current Author Addresses: Drs. Fanelli, Pampanelli, Porcellati, Rossetti, Brunetti, and Bolli: Department of Internal Medicine, University of Perugia, Via E. Dal Pozzo, I-06126 Perugia, Italy.

Author Contributions: Conception and design: C.G. Fanelli, S. Pampanelli, F. Porcellati, P. Rossetti, P. Brunetti, G.B. Bolli.

Analysis and interpretation of the data: C.G. Fanelli, S. Pampanelli, F. Porcellati, P. Brunetti, G.B. Bolli.

Drafting of the article: C.G. Fanelli, S. Pampanelli, F. Porcellati, G.B. Bolli.

Critical revision of the article for important intellectual content: C.G. Fanelli, S. Pampanelli, F. Porcellati, P. Brunetti, G.B. Bolli.

Final approval of the article: C.G. Fanelli, S. Pampanelli, F. Porcellati, P. Rossetti, P. Brunetti, G.B. Bolli.

Provision of study materials or patients: S. Pampanelli, F. Porcellati, P. Rossetti, G.B. Bolli.

Statistical expertise: C.G. Fanelli, G.B. Bolli.

Obtaining of funding: C.G. Fanelli, F. Porcellati, P. Brunetti, G.B. Bolli.

Administrative, technical, or logistic support: P. Brunetti.

Collection and assembly of data: C.G. Fanelli, S. Pampanelli, P. Rossetti.