The Lung As an Alternative Route of Delivery for Insulin in Controlling Postprandial Glucose Levels in Patients With Diabetes

¹ From the Division of Radiation Health Sciences, and the Johns Hopkins University School of Hygiene and Public Health, Baltimore, Maryland
² From the Division of Endocrinology, and the Johns Hopkins University School of Medicine, Baltimore, Maryland

Beth L. Laube, PhD, Room 2001, Johns Hopkins University School of Hygiene and Public Health, 615 North Wolfe St, Baltimore, MD 21205; e-mail: blaube{at}welchlink.welch.jhu.edu

Study objectives: To determine the efficacy of the lung as an alternative route of delivery for insulin in controlling glucose below diabetic levels (11.2 mmol/L) 2 h after the ingestion of a meal in patients with type 2 diabetes mellitus.

Design: Single-blinded, nonrandomized, placebo-controlled pilot study consisting of two visits.

Setting: A primary care facility.

Patients: Seven patients with type 2 diabetes mellitus.

Interventions: On the first study visit, fasting glucose levels were normalized. Then, patients inhaled 1.5 U/kg insulin by aerosol into the lungs 5 min before ingesting a test meal. On the second visit, patients inhaled placebo aerosol 5 min before ingesting the same meal. On both visits, plasma samples were collected and analyzed for glucose levels for 3 h during the postprandial state.

Measurements and results: No one coughed after inhalation of insulin aerosol or demonstrated hypoglycemia. During the postprandial period, glucose levels were significantly lower at 20 min (5.12 ± 1.08 mmol/L), 1 h (7.87 ± 0.73 mmol/L), 2 h (8.05 ± 1.24 mmol/L) and 3 h (7.50 ± 1.43 mmol/L) following inhalation of insulin than when the placebo was used. Data for the placebo were 10.36 ± 1.23 mmol/L at 20 min, 14.0 ± 1.68 mmol/L at 1 h, 16.18 ± 1.45 mmol/L at 2 h, and 14.37 ± 2.11 mmol/L at 3h (for all comparisons, p < 0.05). On the insulin visit, glucose levels were < 11.2 mmol/L 2 h after the meal in six of seven patients. None attained this level at the placebo visit. In addition, glucose levels were within the normal postprandial range of < 7.84 mmol/L in four of seven patients 2 h after eating on the insulin visit.

Conclusions: These results suggest that, once plasma glucose levels are normalized, postprandial glucose levels can be maintained below diabetic levels by delivering 1.5 U/kg insulin into the lungs 5 min before the ingestion of a meal.

Key Words: aerosol • diabetes • insulin • lungs • postprandial glucose

Submitted on February 6, 1998
Accepted on June 18, 1998

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