Table 1 Summary of key low-calorie diet studies in people with type 2 diabetes

Petersen et al. ⁸

Pre- and Post-intervention study conducted in Yale General Clinical Research Center, USA

8 patients (mean age: 47 [SD: 3] years) with type 2 diabetes and BMI ≥ 30 kg/m²

LCD formula (~1200 kcal/day; 50% carbohydrate, 43% protein, 3% fat, 12 g of fiber) for 2 months

None

• Weight loss: 8.0 kg (8.0% of initial weight), p < 0.001

• Liver fat content: 81% reduction from baseline (p = 0.009)

• Hepatic insulin sensitivity: insulin suppression of hepatic glucose output increased from 29% to 93%, p = 0.04

• Fasting plasma glucose: reduced by 43.2 mg/dl (from 158.4 mg/dl to 115.2 mg/dl, p < 0.001)

DiRECT trial, Lean et al. ¹⁶, Taylor et al. ¹⁹

RCT conducted at 46 primary care centers in Scotland and the Tyneside region of England

298 adults (20–65 years) with type 2 diabetes within 6 years of diagnosis and BMI 27–45 kg/m²

LCD (825–853 kcal/day; 59% carbohydrate, 13% fat, 26% protein, 2% fiber) intervention for 3–5 months

Routine diabetes care

In the Tyneside cohort (n = 58):

• Weight loss: 14.8 kg (14.7% of initial weight), p < 0.0001

• Liver fat percent: reduced by 127%, p < 0.0001

• Early-phase insulin secretion: increased by 0.04 nmol/min/m², p < 0.0001

• Fasting plasma glucose: reduced by 27.8 mg/dl, p < 0.0001

DIADEM-I trial, Taheri et al. ¹⁸

RCT conducted in primary care and community settings in Qatar

158 adults (aged 18–50 years) with a short duration (≤3 years) of type 2 diabetes and BMI ≥27.0 kg/m²

An LCD formula (800–820 kcal/day; 57% carbohydrate, 14% fat, 26% protein, 3% fiber) for 3 months

Usual diabetes care

• Weight loss: reduced by 12.0 kg (10.3%) in intervention participants and 4.0 kg (4.8%) in control participants (difference: −6.08 kg, 95% CI −8.37, −3.79; p < 0.0001)

• Insulin sensitivity: improved, as measured by the QUICKI index, by 0.016 points in intervention participants and reduced by 0.006 points in control participants (difference: 0.025, 95% CI 0.015, 0.035; p < 0.001)

STANDby trial, Sattar et al. ¹⁷

RCT conducted in primary care practices in the U.K

25 adults (aged 18–65 years) of South Asian ethnicity with type 2 diabetes for ≤4 years and BMI 25–45 kg/m²

An LCD (825–853 kcal/day; 59% carbohydrate, 13% fat, 26% protein, 2% fiber) intervention for 3–5 months

Usual diabetes care

• Weight loss: reduced by 7.2 kg (7.7%) in the intervention group as compared to 0.9 kg (1.2%) in the control group (difference: −6.3 kg, 95% CI −11.0, −1.6; p = 0.011)

• Fasting plasma glucose: reduced by 18.0 mg/dl in intervention participants and 9.0 mg/dl in control participants (difference: −9.0 mg/dl, 95% CI −34.2, 14.4; p = 0.41)