Purpose: It is generally assumed that diet therapy can ameliorate the metabolic derangements experienced by obese type 2 diabetic patients, thereby leading to discontinuation of insulin or oral sulfonylurea drug therapy. We decided to retrospectively investigate which clinical and biochemical parameters affect therapeutic responses.
Patients and methods: Sixty-four poorly controlled obese diabetic patients were hospitalized and placed on a precisely defined, hypocaloric diet. Known duration of diabetes, type of pharmacologic therapy, body weight, weight loss, fasting plasma glucose concentrations, C-peptide levels, hemoglobin A1C, and plasma lipid levels were assessed, as were nitrogen and electrolyte balances.
Results: Average weight loss was 13 pounds in a mean of 23 days. During hospitalization, the mean fasting plasma glucose value for the group fell from 221 +/- 10 to 122 +/- 5 mg/dl. In 45 patients (73 percent), the final fasting plasma glucose level was less than 125 mg/dl (mean: 102 +/- 2 mg/dl). Oral glucose tolerance even in those patients in whom fasting plasma glucose levels normalized was still grossly diabetic at the end of the hospital stay, deteriorating further after three days of liberalized caloric intake. In part this may have been due to decreased insulin secretory reserve as reflected by blunted plasma C-peptide response. Forty of 42 patients who entered the study taking insulin were able to discontinue the drug within one to seven days of hospitalization. After a mean follow-up period of 19 months, only 10 of 50 patients continued to maintain fasting euglycemia; five were on diet alone, and five were receiving oral hypoglycemic agents. Thirteen patients were receiving insulin therapy.
Conclusion: Diet therapy in these patients resulted in short-term improvement of glycemic control and, in the majority, normalization of fasting plasma glucose levels. However, long-term outpatient follow-up revealed that relapse occurred in most patients.