The combination of insulin and metformin in treatment of non-insulin-dependent diabetes mellitus.
OBJECTIVE
To assess whether, in the treatment of non-insulin-dependent diabetes mellitus (NIDDM), (1) metformin in conjunction with insulin can safely cause a decrease in glycosylated hemoglobin (HbA1c) to 7% or less and (2) this combination therapy may result in weight loss and lower insulin dose in comparison with insulin treatment alone.


METHODS
Forty patients with NIDDM being treated with insulin on their first visit to the Diabetes Center were identified by retrospective review of medical records of all patients encountered during a 1-year period. These patients were classified into groups who were receiving insulin only (group 1) or insulin + metformin (group 2) at the most recent visit. Group 2 was subdivided into those with a body mass index of either =30 kg/m 2 (group 2A) or >30 kg/m 2 (group 2B). Blood glucose, HbA1c, insulin dose, and weights were analyzed from their initial and most recent visits.


RESULTS
HbA1c decreased from 10 +/- 2.7% to 7 +/- 1.1% (P<0.01) in group 1 and from 9.8 +/- 2.1% to 7.2 +/- 1.4% (P<0.01) in group 2. The magnitude of decrease in HbA1c, however, was not different between the two groups. Total insulin dose increased from 40 (33 to 50) U/day to 58 (41 to 67) U/day (P<0.05) in group 1 and from 63 (42 to 118) U/day to 67 (50 to 96) U/day in group 2 (not significantly different). The median increase in insulin dose was 8 U in group 1, whereas the median decrease was 3 U in group 2 (P<0.05). Similar decreases were noted in group 2A. The decrease in insulin dose was inversely related to the initial insulin dose per kilogram of body weight in group 2 (r = -0.5; P<0.01). Patients in group 1 had an increase in weight from 75.0 +/- 8.6 kg to 77.7 +/- 9.0 kg (P<0.01), whereas weight decreased from 100.4 +/- 24.2 kg to 98.5 +/- 22.3 kg in group 2 (P<0.05). A decrease in weight was seen even in group 2A. The increase in weight was 3 +/- 3.3 kg in group 1, whereas weight decreased by 1.9 +/- 3.9 kg in group 2 (P<0.01).


CONCLUSIONS
Insulin + metformin is safe and is as effective as insulin alone in improving glycemic control in obese and nonobese patients with NIDDM. This combination therapy, however, lowers insulin dose and promotes weight loss, which may be of importance in decreasing the cardiovascular risk factors in these subjects.
Chaudhuri
A
A
Division of Endocrinology, State University of New York at Buffalo, Millard Fillmore Health System, Buffalo, New York 14209, USA.
Tomar
R
R
Mohanty
P
P
Szudzik
E
E
Bandyopadhyay
A
A
Arian
M
M
Thusu
K
K
Dandona
P
P