BACKGROUND: Type 2 diabetes usually occurs in the context of obesity and associated insulin resistance. Current treatment recommendations are based on lifestyle modifications and incremental drug therapy. However, this approach could lead to inappropriate priorities upon ageing, when diabetes may be compounded by malnutrition and reduced insulin resistance. METHODS: We prospectively evaluated glycaemic and nutritional parameters in 146 consecutive diabetic patients (age 82.5 +/- 7.3 years, mean +/- sd) admitted to our geriatric service. We also implemented nutritional support therapy and a drug therapy adjustment protocol. Oral hypoglycaemic agent withdrawal was attempted in cases of good glycaemic control (HbA(1c) < 7.5% (<47 mmol/mol) or fasting blood glucose < 7.5 mmol/l). RESULTS: Mean BMI and HbA(1c) were 29.6 +/- 7.1 kg/m(2) and 6.9 +/- 1.2% (52 +/- 9 mmol/mol), respectively. Of the patients, 51.4% were taking 1-3 oral hypoglycaemic agents, 30.8% were on insulin and 9.6% on were on insulin and oral hypoglycaemic therapy. Low Mini Nutritional Assessment scores and serum marker levels indicated a high prevalence of malnutrition and/or chronic disease, even in obese patients. Mini Nutritional Assessment scores were positively associated with HbA(1c) values. Among patients treated by oral hypoglycaemic agents, complete drug withdrawal was achieved in 65.8%, much more often than new treatments were added (P = 0.002). Glycaemic control did not worsen after approximately 30 days, despite in-hospital nutritional therapy. Successful oral hypoglycaemic therapy withdrawal was associated with lower Mini Nutritional Assessment scores. CONCLUSIONS: Malnutrition is highly prevalent in elderly diabetic inpatients and, paradoxically, contributes to 'good' glycaemic control. Malnutrition should be screened for in these patients and, when present, should prompt a revision in diet and drug therapy. In particular, the possibility of reducing unnecessary drug therapy should be considered.